//! Contains builtins that deal with the store or builder.

use std::rc::Rc;

use crate::tvix_store_io::TvixStoreIO;

mod derivation;
mod errors;
mod fetchers;
mod import;
mod utils;

pub use errors::{DerivationError, FetcherError, ImportError};

/// Adds derivation-related builtins to the passed [tvix_eval::Evaluation].
///
/// These are `derivation` and `derivationStrict`.
///
/// As they need to interact with `known_paths`, we also need to pass in
/// `known_paths`.
pub fn add_derivation_builtins<'co, 'ro, 'env, IO>(
    eval_builder: tvix_eval::EvaluationBuilder<'co, 'ro, 'env, IO>,
    io: Rc<TvixStoreIO>,
) -> tvix_eval::EvaluationBuilder<'co, 'ro, 'env, IO> {
    eval_builder
        .add_builtins(derivation::derivation_builtins::builtins(Rc::clone(&io)))
        // Add the actual `builtins.derivation` from compiled Nix code
        .add_src_builtin("derivation", include_str!("derivation.nix"))
}

/// Adds fetcher builtins to the passed [tvix_eval::Evaluation]:
///
/// * `fetchurl`
/// * `fetchTarball`
/// * `fetchGit`
pub fn add_fetcher_builtins<'co, 'ro, 'env, IO>(
    eval_builder: tvix_eval::EvaluationBuilder<'co, 'ro, 'env, IO>,
    io: Rc<TvixStoreIO>,
) -> tvix_eval::EvaluationBuilder<'co, 'ro, 'env, IO> {
    eval_builder.add_builtins(fetchers::fetcher_builtins::builtins(Rc::clone(&io)))
}

/// Adds import-related builtins to the passed [tvix_eval::Evaluation].
///
/// These are `filterSource` and `path`
///
/// As they need to interact with the store implementation, we pass [`TvixStoreIO`].
pub fn add_import_builtins<'co, 'ro, 'env, IO>(
    eval_builder: tvix_eval::EvaluationBuilder<'co, 'ro, 'env, IO>,
    io: Rc<TvixStoreIO>,
) -> tvix_eval::EvaluationBuilder<'co, 'ro, 'env, IO> {
    // TODO(raitobezarius): evaluate expressing filterSource as Nix code using path (b/372)
    eval_builder.add_builtins(import::import_builtins(io))
}

#[cfg(test)]
mod tests {
    use std::{fs, rc::Rc, sync::Arc};

    use crate::tvix_store_io::TvixStoreIO;

    use super::{add_derivation_builtins, add_fetcher_builtins, add_import_builtins};
    use nix_compat::store_path::hash_placeholder;
    use rstest::rstest;
    use tempfile::TempDir;
    use tvix_build::buildservice::DummyBuildService;
    use tvix_eval::{EvalIO, EvaluationResult};
    use tvix_store::utils::construct_services;

    /// evaluates a given nix expression and returns the result.
    /// Takes care of setting up the evaluator so it knows about the
    // `derivation` builtin.
    fn eval(str: &str) -> EvaluationResult {
        // We assemble a complete store in memory.
        let runtime = tokio::runtime::Runtime::new().expect("Failed to build a Tokio runtime");
        let (blob_service, directory_service, path_info_service, nar_calculation_service) = runtime
            .block_on(async { construct_services("memory://", "memory://", "memory://").await })
            .expect("Failed to construct store services in memory");

        let io = Rc::new(TvixStoreIO::new(
            blob_service,
            directory_service,
            path_info_service,
            nar_calculation_service.into(),
            Arc::<DummyBuildService>::default(),
            runtime.handle().clone(),
        ));

        let mut eval_builder = tvix_eval::Evaluation::builder(io.clone() as Rc<dyn EvalIO>);
        eval_builder = add_derivation_builtins(eval_builder, Rc::clone(&io));
        eval_builder = add_fetcher_builtins(eval_builder, Rc::clone(&io));
        eval_builder = add_import_builtins(eval_builder, io);
        let eval = eval_builder.build();

        // run the evaluation itself.
        eval.evaluate(str, None)
    }

    #[test]
    fn derivation() {
        let result = eval(
            r#"(derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux";}).outPath"#,
        );

        assert!(result.errors.is_empty(), "expect evaluation to succeed");
        let value = result.value.expect("must be some");

        match value {
            tvix_eval::Value::String(s) => {
                assert_eq!(*s, "/nix/store/xpcvxsx5sw4rbq666blz6sxqlmsqphmr-foo",);
            }
            _ => panic!("unexpected value type: {:?}", value),
        }
    }

    /// a derivation with an empty name is an error.
    #[test]
    fn derivation_empty_name_fail() {
        let result = eval(
            r#"(derivation { name = ""; builder = "/bin/sh"; system = "x86_64-linux";}).outPath"#,
        );

        assert!(!result.errors.is_empty(), "expect evaluation to fail");
    }

    /// construct some calls to builtins.derivation and compare produced output
    /// paths.
    #[rstest]
    #[case::r_sha256(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "recursive"; outputHashAlgo = "sha256"; outputHash = "sha256-Q3QXOoy+iN4VK2CflvRulYvPZXYgF0dO7FoF7CvWFTA="; }).outPath"#, "/nix/store/17wgs52s7kcamcyin4ja58njkf91ipq8-foo")]
    #[case::r_sha256_other_name(r#"(builtins.derivation { name = "foo2"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "recursive"; outputHashAlgo = "sha256"; outputHash = "sha256-Q3QXOoy+iN4VK2CflvRulYvPZXYgF0dO7FoF7CvWFTA="; }).outPath"#, "/nix/store/gi0p8vd635vpk1nq029cz3aa3jkhar5k-foo2")]
    #[case::r_sha1(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "recursive"; outputHashAlgo = "sha1"; outputHash = "sha1-VUCRC+16gU5lcrLYHlPSUyx0Y/Q="; }).outPath"#, "/nix/store/p5sammmhpa84ama7ymkbgwwzrilva24x-foo")]
    #[case::r_md5(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "recursive"; outputHashAlgo = "md5"; outputHash = "md5-07BzhNET7exJ6qYjitX/AA=="; }).outPath"#, "/nix/store/gmmxgpy1jrzs86r5y05wy6wiy2m15xgi-foo")]
    #[case::r_sha512(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "recursive"; outputHashAlgo = "sha512"; outputHash = "sha512-DPkYCnZKuoY6Z7bXLwkYvBMcZ3JkLLLc5aNPCnAvlHDdwr8SXBIZixmVwjPDS0r9NGxUojNMNQqUilG26LTmtg=="; }).outPath"#, "/nix/store/lfi2bfyyap88y45mfdwi4j99gkaxaj19-foo")]
    #[case::r_sha256_base16(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "recursive"; outputHashAlgo = "sha256"; outputHash = "4374173a8cbe88de152b609f96f46e958bcf65762017474eec5a05ec2bd61530"; }).outPath"#, "/nix/store/17wgs52s7kcamcyin4ja58njkf91ipq8-foo")]
    #[case::r_sha256_nixbase32(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "recursive"; outputHashAlgo = "sha256"; outputHash = "0c0msqmyq1asxi74f5r0frjwz2wmdvs9d7v05caxx25yihx1fx23"; }).outPath"#, "/nix/store/17wgs52s7kcamcyin4ja58njkf91ipq8-foo")]
    #[case::r_sha256_base64(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "recursive"; outputHashAlgo = "sha256"; outputHash = "Q3QXOoy+iN4VK2CflvRulYvPZXYgF0dO7FoF7CvWFTA="; }).outPath"#, "/nix/store/17wgs52s7kcamcyin4ja58njkf91ipq8-foo")]
    #[case::r_sha256_base64_nopad(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "recursive"; outputHashAlgo = "sha256"; outputHash = "sha256-fgIr3TyFGDAXP5+qoAaiMKDg/a1MlT6Fv/S/DaA24S8="; }).outPath"#, "/nix/store/xm1l9dx4zgycv9qdhcqqvji1z88z534b-foo")]
    #[case::sha256(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "flat"; outputHashAlgo = "sha256"; outputHash = "sha256-Q3QXOoy+iN4VK2CflvRulYvPZXYgF0dO7FoF7CvWFTA="; }).outPath"#, "/nix/store/q4pkwkxdib797fhk22p0k3g1q32jmxvf-foo")]
    #[case::sha256_other_name(r#"(builtins.derivation { name = "foo2"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "flat"; outputHashAlgo = "sha256"; outputHash = "sha256-Q3QXOoy+iN4VK2CflvRulYvPZXYgF0dO7FoF7CvWFTA="; }).outPath"#, "/nix/store/znw17xlmx9r6gw8izjkqxkl6s28sza4l-foo2")]
    #[case::sha1(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "flat"; outputHashAlgo = "sha1"; outputHash = "sha1-VUCRC+16gU5lcrLYHlPSUyx0Y/Q="; }).outPath"#, "/nix/store/zgpnjjmga53d8srp8chh3m9fn7nnbdv6-foo")]
    #[case::md5(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "flat"; outputHashAlgo = "md5"; outputHash = "md5-07BzhNET7exJ6qYjitX/AA=="; }).outPath"#, "/nix/store/jfhcwnq1852ccy9ad9nakybp2wadngnd-foo")]
    #[case::sha512(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "flat"; outputHashAlgo = "sha512"; outputHash = "sha512-DPkYCnZKuoY6Z7bXLwkYvBMcZ3JkLLLc5aNPCnAvlHDdwr8SXBIZixmVwjPDS0r9NGxUojNMNQqUilG26LTmtg=="; }).outPath"#, "/nix/store/as736rr116ian9qzg457f96j52ki8bm3-foo")]
    #[case::r_sha256_outputhashalgo_omitted(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "recursive"; outputHash = "sha256-Q3QXOoy+iN4VK2CflvRulYvPZXYgF0dO7FoF7CvWFTA="; }).outPath"#, "/nix/store/17wgs52s7kcamcyin4ja58njkf91ipq8-foo")]
    #[case::r_sha256_outputhashalgo_and_outputhashmode_omitted(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHash = "sha256-Q3QXOoy+iN4VK2CflvRulYvPZXYgF0dO7FoF7CvWFTA="; }).outPath"#, "/nix/store/q4pkwkxdib797fhk22p0k3g1q32jmxvf-foo")]
    #[case::outputhash_omitted(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; }).outPath"#, "/nix/store/xpcvxsx5sw4rbq666blz6sxqlmsqphmr-foo")]
    #[case::multiple_outputs(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; outputs = ["foo" "bar"]; system = "x86_64-linux"; }).outPath"#, "/nix/store/hkwdinvz2jpzgnjy9lv34d2zxvclj4s3-foo-foo")]
    #[case::args(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; args = ["--foo" "42" "--bar"]; system = "x86_64-linux"; }).outPath"#, "/nix/store/365gi78n2z7vwc1bvgb98k0a9cqfp6as-foo")]
    #[case::full(r#"
                   let
                     bar = builtins.derivation {
                       name = "bar";
                       builder = ":";
                       system = ":";
                       outputHash = "08813cbee9903c62be4c5027726a418a300da4500b2d369d3af9286f4815ceba";
                       outputHashAlgo = "sha256";
                       outputHashMode = "recursive";
                     };
                   in
                   (builtins.derivation {
                     name = "foo";
                     builder = ":";
                     system = ":";
                     inherit bar;
                   }).outPath
        "#, "/nix/store/5vyvcwah9l9kf07d52rcgdk70g2f4y13-foo")]
    #[case::pass_as_file(r#"(builtins.derivation { "name" = "foo"; passAsFile = ["bar"]; bar = "baz"; system = ":"; builder = ":";}).outPath"#, "/nix/store/25gf0r1ikgmh4vchrn8qlc4fnqlsa5a1-foo")]
    // __ignoreNulls = true, but nothing set to null
    #[case::ignore_nulls_true_no_arg_drvpath(r#"(builtins.derivation { name = "foo"; system = ":"; builder = ":"; __ignoreNulls = true; }).drvPath"#, "/nix/store/xa96w6d7fxrlkk60z1fmx2ffp2wzmbqx-foo.drv")]
    #[case::ignore_nulls_true_no_arg_outpath(r#"(builtins.derivation { name = "foo"; system = ":"; builder = ":"; __ignoreNulls = true; }).outPath"#, "/nix/store/pk2agn9za8r9bxsflgh1y7fyyrmwcqkn-foo")]
    // __ignoreNulls = true, with a null arg, same paths
    #[case::ignore_nulls_true_drvpath(r#"(builtins.derivation { name = "foo"; system = ":"; builder = ":"; __ignoreNulls = true; ignoreme = null; }).drvPath"#, "/nix/store/xa96w6d7fxrlkk60z1fmx2ffp2wzmbqx-foo.drv")]
    #[case::ignore_nulls_true_outpath(r#"(builtins.derivation { name = "foo"; system = ":"; builder = ":"; __ignoreNulls = true; ignoreme = null; }).outPath"#, "/nix/store/pk2agn9za8r9bxsflgh1y7fyyrmwcqkn-foo")]
    // __ignoreNulls = false
    #[case::ignore_nulls_false_no_arg_drvpath(r#"(builtins.derivation { name = "foo"; system = ":"; builder = ":"; __ignoreNulls = false; }).drvPath"#, "/nix/store/xa96w6d7fxrlkk60z1fmx2ffp2wzmbqx-foo.drv")]
    #[case::ignore_nulls_false_no_arg_outpath(r#"(builtins.derivation { name = "foo"; system = ":"; builder = ":"; __ignoreNulls = false; }).outPath"#, "/nix/store/pk2agn9za8r9bxsflgh1y7fyyrmwcqkn-foo")]
    // __ignoreNulls = false, with a null arg
    #[case::ignore_nulls_fales_arg_path_drvpath(r#"(builtins.derivation { name = "foo"; system = ":"; builder = ":"; __ignoreNulls = false; foo = null; }).drvPath"#, "/nix/store/xwkwbajfiyhdqmksrbzm0s4g4ib8d4ms-foo.drv")]
    #[case::ignore_nulls_fales_arg_path_outpath(r#"(builtins.derivation { name = "foo"; system = ":"; builder = ":"; __ignoreNulls = false; foo = null; }).outPath"#, "/nix/store/2n2jqm6l7r2ahi19m58pl896ipx9cyx6-foo")]
    // structured attrs set to false will render an empty string inside env
    #[case::structured_attrs_false_drvpath(r#"(builtins.derivation { name = "foo"; system = ":"; builder = ":"; __structuredAttrs = false; foo = "bar"; }).drvPath"#, "/nix/store/qs39krwr2lsw6ac910vqx4pnk6m63333-foo.drv")]
    #[case::structured_attrs_false_outpath(r#"(builtins.derivation { name = "foo"; system = ":"; builder = ":"; __structuredAttrs = false; foo = "bar"; }).outPath"#, "/nix/store/9yy3764rdip3fbm8ckaw4j9y7vh4d231-foo")]
    // simple structured attrs
    #[case::structured_attrs_simple_drvpath(r#"(builtins.derivation { name = "foo"; system = ":"; builder = ":"; __structuredAttrs = true; foo = "bar"; }).drvPath"#, "/nix/store/k6rlb4k10cb9iay283037ml1nv3xma2f-foo.drv")]
    #[case::structured_attrs_simple_outpath(r#"(builtins.derivation { name = "foo"; system = ":"; builder = ":"; __structuredAttrs = true; foo = "bar"; }).outPath"#, "/nix/store/6lmv3hyha1g4cb426iwjyifd7nrdv1xn-foo")]
    // structured attrs with outputsCheck
    #[case::structured_attrs_output_checks_drvpath(r#"(builtins.derivation { name = "foo"; system = ":"; builder = ":"; __structuredAttrs = true; foo = "bar"; outputChecks = {out = {maxClosureSize = 256 * 1024 * 1024; disallowedRequisites = [ "dev" ];};}; }).drvPath"#, "/nix/store/fx9qzpchh5wchchhy39bwsml978d6wp1-foo.drv")]
    #[case::structured_attrs_output_checks_outpath(r#"(builtins.derivation { name = "foo"; system = ":"; builder = ":"; __structuredAttrs = true; foo = "bar"; outputChecks = {out = {maxClosureSize = 256 * 1024 * 1024; disallowedRequisites = [ "dev" ];};}; }).outPath"#, "/nix/store/pcywah1nwym69rzqdvpp03sphfjgyw1l-foo")]
    // structured attrs and __ignoreNulls. ignoreNulls is inactive (so foo ends up in __json, yet __ignoreNulls itself is not present.
    #[case::structured_attrs_and_ignore_nulls_drvpath(r#"(builtins.derivation { name = "foo"; system = ":"; builder = ":"; __ignoreNulls = false; foo = null; __structuredAttrs = true; }).drvPath"#, "/nix/store/rldskjdcwa3p7x5bqy3r217va1jsbjsc-foo.drv")]
    // structured attrs, setting outputs.
    #[case::structured_attrs_outputs_drvpath(r#"(builtins.derivation { name = "test"; system = "aarch64-linux"; builder = "/bin/sh"; __structuredAttrs = true; outputs = [ "out"]; }).drvPath"#, "/nix/store/6sgawp30zibsh525p7c948xxd22y2ngy-test.drv")]
    fn test_outpath(#[case] code: &str, #[case] expected_path: &str) {
        let value = eval(code).value.expect("must succeed");

        match value {
            tvix_eval::Value::String(s) => {
                assert_eq!(*s, expected_path);
            }
            _ => panic!("unexpected value type: {:?}", value),
        }
    }

    /// construct some calls to builtins.derivation that should be rejected
    #[rstest]
    #[case::invalid_outputhash(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "recursive"; outputHashAlgo = "sha256"; outputHash = "sha256-00"; }).outPath"#)]
    #[case::sha1_and_sha256(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "recursive"; outputHashAlgo = "sha1"; outputHash = "sha256-Q3QXOoy+iN4VK2CflvRulYvPZXYgF0dO7FoF7CvWFTA="; }).outPath"#)]
    #[case::duplicate_output_names(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; outputs = ["foo" "foo"]; system = "x86_64-linux"; }).outPath"#)]
    fn test_outpath_invalid(#[case] code: &str) {
        let resp = eval(code);
        assert!(resp.value.is_none(), "Value should be None");
        assert!(
            !resp.errors.is_empty(),
            "There should have been some errors"
        );
    }

    /// Construct two FODs with the same name, and same known output (but
    /// slightly different recipe), ensure they have the same output hash.
    #[test]
    fn test_fod_outpath() {
        let code = r#"
          (builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHash = "sha256-Q3QXOoy+iN4VK2CflvRulYvPZXYgF0dO7FoF7CvWFTA="; }).outPath ==
          (builtins.derivation { name = "foo"; builder = "/bin/aa"; system = "x86_64-linux"; outputHash = "sha256-Q3QXOoy+iN4VK2CflvRulYvPZXYgF0dO7FoF7CvWFTA="; }).outPath
        "#;

        let value = eval(code).value.expect("must succeed");
        match value {
            tvix_eval::Value::Bool(v) => {
                assert!(v);
            }
            _ => panic!("unexpected value type: {:?}", value),
        }
    }

    /// Construct two FODs with the same name, and same known output (but
    /// slightly different recipe), ensure they have the same output hash.
    #[test]
    fn test_fod_outpath_different_name() {
        let code = r#"
          (builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHash = "sha256-Q3QXOoy+iN4VK2CflvRulYvPZXYgF0dO7FoF7CvWFTA="; }).outPath ==
          (builtins.derivation { name = "foo"; builder = "/bin/aa"; system = "x86_64-linux"; outputHash = "sha256-Q3QXOoy+iN4VK2CflvRulYvPZXYgF0dO7FoF7CvWFTA="; }).outPath
        "#;

        let value = eval(code).value.expect("must succeed");
        match value {
            tvix_eval::Value::Bool(v) => {
                assert!(v);
            }
            _ => panic!("unexpected value type: {:?}", value),
        }
    }

    /// Construct two derivations with the same parameters except one of them lost a context string
    /// for a dependency, causing the loss of an element in the `inputDrvs` derivation. Therefore,
    /// making `outPath` different.
    #[test]
    fn test_unsafe_discard_string_context() {
        let code = r#"
        let
            dep = builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; };
        in
          (builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; env = "${dep}"; }).outPath !=
          (builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; env = "${builtins.unsafeDiscardStringContext dep}"; }).outPath
        "#;

        let value = eval(code).value.expect("must succeed");
        match value {
            tvix_eval::Value::Bool(v) => {
                assert!(v);
            }
            _ => panic!("unexpected value type: {:?}", value),
        }
    }

    /// Construct an attribute set that coerces to a derivation and verify that the return type is
    /// a string.
    #[test]
    fn test_unsafe_discard_string_context_of_coercible() {
        let code = r#"
        let
            dep = builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; };
            attr = { __toString = _: dep; };
        in
            builtins.typeOf (builtins.unsafeDiscardStringContext attr) == "string"
        "#;

        let value = eval(code).value.expect("must succeed");
        match value {
            tvix_eval::Value::Bool(v) => {
                assert!(v);
            }
            _ => panic!("unexpected value type: {:?}", value),
        }
    }

    #[rstest]
    #[case::input_in_args(r#"
                   let
                     bar = builtins.derivation {
                       name = "bar";
                       builder = ":";
                       system = ":";
                       outputHash = "08813cbee9903c62be4c5027726a418a300da4500b2d369d3af9286f4815ceba";
                       outputHashAlgo = "sha256";
                       outputHashMode = "recursive";
                     };
                   in
                   (builtins.derivation {
                     name = "foo";
                     builder = ":";
                     args = [ "${bar}" ];
                     system = ":";
                   }).drvPath
        "#, "/nix/store/50yl2gmmljyl0lzyrp1mcyhn53vhjhkd-foo.drv")]
    fn test_inputs_derivation_from_context(#[case] code: &str, #[case] expected_drvpath: &str) {
        let eval_result = eval(code);

        let value = eval_result.value.expect("must succeed");

        match value {
            tvix_eval::Value::String(s) => {
                assert_eq!(*s, expected_drvpath);
            }

            _ => panic!("unexpected value type: {:?}", value),
        };
    }

    #[test]
    fn builtins_placeholder_hashes() {
        assert_eq!(
            hash_placeholder("out").as_str(),
            "/1rz4g4znpzjwh1xymhjpm42vipw92pr73vdgl6xs1hycac8kf2n9"
        );

        assert_eq!(
            hash_placeholder("").as_str(),
            "/171rf4jhx57xqz3p7swniwkig249cif71pa08p80mgaf0mqz5bmr"
        );
    }

    /// constructs calls to builtins.derivation that should succeed, but produce warnings
    #[rstest]
    #[case::r_sha256_wrong_padding(r#"(builtins.derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; outputHashMode = "recursive"; outputHashAlgo = "sha256"; outputHash = "sha256-fgIr3TyFGDAXP5+qoAaiMKDg/a1MlT6Fv/S/DaA24S8===="; }).outPath"#, "/nix/store/xm1l9dx4zgycv9qdhcqqvji1z88z534b-foo")]
    fn builtins_derivation_hash_wrong_padding_warn(
        #[case] code: &str,
        #[case] expected_path: &str,
    ) {
        let eval_result = eval(code);

        let value = eval_result.value.expect("must succeed");

        match value {
            tvix_eval::Value::String(s) => {
                assert_eq!(*s, expected_path);
            }
            _ => panic!("unexpected value type: {:?}", value),
        }

        assert!(
            !eval_result.warnings.is_empty(),
            "warnings should not be empty"
        );
    }

    /// Invokes `builtins.filterSource` on various carefully-crated subdirs, and
    /// ensures the resulting store paths matches what Nix produces.
    /// @fixtures is replaced to the fixtures directory.
    #[rstest]
    #[cfg(target_family = "unix")]
    #[case::complicated_filter_nothing(
        r#"(builtins.filterSource (p: t: true) @fixtures)"#,
        "/nix/store/bqh6kd0x3vps2rzagzpl7qmbbgnx19cp-import_fixtures"
    )]
    #[case::complicated_filter_everything(
        r#"(builtins.filterSource (p: t: false) @fixtures)"#,
        "/nix/store/giq6czz24lpjg97xxcxk6rg950lcpib1-import_fixtures"
    )]
    #[case::simple_dir_with_one_file_filter_dirs(
        r#"(builtins.filterSource (p: t: t != "directory") @fixtures/a_dir)"#,
        "/nix/store/8vbqaxapywkvv1hacdja3pi075r14d43-a_dir"
    )]
    #[case::simple_dir_with_one_file_filter_files(
        r#"(builtins.filterSource (p: t: t != "regular") @fixtures/a_dir)"#,
        "/nix/store/zphlqc93s2iq4xm393l06hzf8hp85r4z-a_dir"
    )]
    #[case::simple_dir_with_one_file_filter_symlinks(
        r#"(builtins.filterSource (p: t: t != "symlink") @fixtures/a_dir)"#,
        "/nix/store/8vbqaxapywkvv1hacdja3pi075r14d43-a_dir"
    )]
    #[case::simple_dir_with_one_file_filter_nothing(
        r#"(builtins.filterSource (p: t: true) @fixtures/a_dir)"#,
        "/nix/store/8vbqaxapywkvv1hacdja3pi075r14d43-a_dir"
    )]
    #[case::simple_dir_with_one_file_filter_everything(
        r#"(builtins.filterSource (p: t: false) @fixtures/a_dir)"#,
        "/nix/store/zphlqc93s2iq4xm393l06hzf8hp85r4z-a_dir"
    )]
    #[case::simple_dir_with_one_dir_filter_dirs(
        r#"builtins.filterSource (p: t: t != "directory") @fixtures/b_dir"#,
        "/nix/store/xzsfzdgrxg93icaamjm8zq1jq6xvf2fz-b_dir"
    )]
    #[case::simple_dir_with_one_dir_filter_files(
        r#"builtins.filterSource (p: t: t != "regular") @fixtures/b_dir"#,
        "/nix/store/8rjx64mm7173xp60rahv7cl3ixfkv3rf-b_dir"
    )]
    #[case::simple_dir_with_one_dir_filter_symlinks(
        r#"builtins.filterSource (p: t: t != "symlink") @fixtures/b_dir"#,
        "/nix/store/8rjx64mm7173xp60rahv7cl3ixfkv3rf-b_dir"
    )]
    #[case::simple_dir_with_one_dir_filter_nothing(
        r#"builtins.filterSource (p: t: true) @fixtures/b_dir"#,
        "/nix/store/8rjx64mm7173xp60rahv7cl3ixfkv3rf-b_dir"
    )]
    #[case::simple_dir_with_one_dir_filter_everything(
        r#"builtins.filterSource (p: t: false) @fixtures/b_dir"#,
        "/nix/store/xzsfzdgrxg93icaamjm8zq1jq6xvf2fz-b_dir"
    )]
    #[case::simple_dir_with_one_symlink_to_file_filter_dirs(
        r#"builtins.filterSource (p: t: t != "directory") @fixtures/c_dir"#,
        "/nix/store/riigfmmzzrq65zqiffcjk5sbqr9c9h09-c_dir"
    )]
    #[case::simple_dir_with_one_symlink_to_file_filter_files(
        r#"builtins.filterSource (p: t: t != "regular") @fixtures/c_dir"#,
        "/nix/store/riigfmmzzrq65zqiffcjk5sbqr9c9h09-c_dir"
    )]
    #[case::simple_dir_with_one_symlink_to_file_filter_symlinks(
        r#"builtins.filterSource (p: t: t != "symlink") @fixtures/c_dir"#,
        "/nix/store/y5g1fz04vzjvf422q92qmv532axj5q26-c_dir"
    )]
    #[case::simple_dir_with_one_symlink_to_file_filter_nothing(
        r#"builtins.filterSource (p: t: true) @fixtures/c_dir"#,
        "/nix/store/riigfmmzzrq65zqiffcjk5sbqr9c9h09-c_dir"
    )]
    #[case::simple_dir_with_one_symlink_to_file_filter_everything(
        r#"builtins.filterSource (p: t: false) @fixtures/c_dir"#,
        "/nix/store/y5g1fz04vzjvf422q92qmv532axj5q26-c_dir"
    )]
    #[case::simple_dir_with_dangling_symlink_filter_dirs(
        r#"builtins.filterSource (p: t: t != "directory") @fixtures/d_dir"#,
        "/nix/store/f2d1aixwiqy4lbzrd040ala2s4m2z199-d_dir"
    )]
    #[case::simple_dir_with_dangling_symlink_filter_files(
        r#"builtins.filterSource (p: t: t != "regular") @fixtures/d_dir"#,
        "/nix/store/f2d1aixwiqy4lbzrd040ala2s4m2z199-d_dir"
    )]
    #[case::simple_dir_with_dangling_symlink_filter_symlinks(
        r#"builtins.filterSource (p: t: t != "symlink") @fixtures/d_dir"#,
        "/nix/store/7l371xax8kknhpska4wrmyll1mzlhzvl-d_dir"
    )]
    #[case::simple_dir_with_dangling_symlink_filter_nothing(
        r#"builtins.filterSource (p: t: true) @fixtures/d_dir"#,
        "/nix/store/f2d1aixwiqy4lbzrd040ala2s4m2z199-d_dir"
    )]
    #[case::simple_dir_with_dangling_symlink_filter_everything(
        r#"builtins.filterSource (p: t: false) @fixtures/d_dir"#,
        "/nix/store/7l371xax8kknhpska4wrmyll1mzlhzvl-d_dir"
    )]
    #[case::simple_symlinked_dir_with_one_file_filter_dirs(
        r#"builtins.filterSource (p: t: t != "directory") @fixtures/symlink_to_a_dir"#,
        "/nix/store/apmdprm8fwl2zrjpbyfcd99zrnhvf47q-symlink_to_a_dir"
    )]
    #[case::simple_symlinked_dir_with_one_file_filter_files(
        r#"builtins.filterSource (p: t: t != "regular") @fixtures/symlink_to_a_dir"#,
        "/nix/store/apmdprm8fwl2zrjpbyfcd99zrnhvf47q-symlink_to_a_dir"
    )]
    #[case::simple_symlinked_dir_with_one_file_filter_symlinks(
        r#"builtins.filterSource (p: t: t != "symlink") @fixtures/symlink_to_a_dir"#,
        "/nix/store/apmdprm8fwl2zrjpbyfcd99zrnhvf47q-symlink_to_a_dir"
    )]
    #[case::simple_symlinked_dir_with_one_file_filter_nothing(
        r#"builtins.filterSource (p: t: true) @fixtures/symlink_to_a_dir"#,
        "/nix/store/apmdprm8fwl2zrjpbyfcd99zrnhvf47q-symlink_to_a_dir"
    )]
    #[case::simple_symlinked_dir_with_one_file_filter_everything(
        r#"builtins.filterSource (p: t: false) @fixtures/symlink_to_a_dir"#,
        "/nix/store/apmdprm8fwl2zrjpbyfcd99zrnhvf47q-symlink_to_a_dir"
    )]
    fn builtins_filter_source_succeed(#[case] code: &str, #[case] expected_outpath: &str) {
        // populate the fixtures dir
        let temp = TempDir::new().expect("create temporary directory");
        let p = temp.path().join("import_fixtures");

        // create the fixtures directory.
        // We produce them at runtime rather than shipping it inside the source
        // tree, as git can't model certain things - like directories without any
        // items.
        {
            fs::create_dir(&p).expect("creating import_fixtures");

            // `/a_dir` contains an empty `a_file` file
            fs::create_dir(p.join("a_dir")).expect("creating /a_dir");
            fs::write(p.join("a_dir").join("a_file"), "").expect("creating /a_dir/a_file");

            // `/a_file` is an empty file
            fs::write(p.join("a_file"), "").expect("creating /a_file");

            // `/b_dir` contains an empty "a_dir" directory
            fs::create_dir_all(p.join("b_dir").join("a_dir")).expect("creating /b_dir/a_dir");

            // `/c_dir` contains a `symlink_to_a_file` symlink, pointing to `../a_dir/a_file`.
            fs::create_dir(p.join("c_dir")).expect("creating /c_dir");
            std::os::unix::fs::symlink(
                "../a_dir/a_file",
                p.join("c_dir").join("symlink_to_a_file"),
            )
            .expect("creating /c_dir/symlink_to_a_file");

            // `/d_dir` contains a `dangling_symlink`, pointing to `a_dir/a_file`,
            // which does not exist.
            fs::create_dir(p.join("d_dir")).expect("creating /d_dir");
            std::os::unix::fs::symlink("a_dir/a_file", p.join("d_dir").join("dangling_symlink"))
                .expect("creating /d_dir/dangling_symlink");

            // `/symlink_to_a_dir` is a symlink to `a_dir`, which exists.
            std::os::unix::fs::symlink("a_dir", p.join("symlink_to_a_dir"))
                .expect("creating /symlink_to_a_dir");
        }

        // replace @fixtures with the temporary path containing the fixtures
        let code_replaced = code.replace("@fixtures", &p.to_string_lossy());

        let eval_result = eval(&code_replaced);

        let value = eval_result.value.expect("must succeed");

        match value {
            tvix_eval::Value::String(s) => {
                assert_eq!(expected_outpath, s.as_bstr());
            }
            _ => panic!("unexpected value type: {:?}", value),
        }

        assert!(eval_result.errors.is_empty(), "errors should be empty");
    }

    // Space is an illegal character.
    #[rstest]
    #[case(
        r#"(builtins.path { name = "valid-name"; path = @fixtures + "/te st"; recursive = true; })"#,
        true
    )]
    // Space is still an illegal character.
    #[case(
        r#"(builtins.path { name = "invalid name"; path = @fixtures + "/te st"; recursive = true; })"#,
        false
    )]
    fn builtins_path_recursive_rename(#[case] code: &str, #[case] success: bool) {
        // populate the fixtures dir
        let temp = TempDir::new().expect("create temporary directory");
        let p = temp.path().join("import_fixtures");

        // create the fixtures directory.
        // We produce them at runtime rather than shipping it inside the source
        // tree, as git can't model certain things - like directories without any
        // items.
        {
            fs::create_dir(&p).expect("creating import_fixtures");
            fs::write(p.join("te st"), "").expect("creating `/te st`");
        }
        // replace @fixtures with the temporary path containing the fixtures
        let code_replaced = code.replace("@fixtures", &p.to_string_lossy());

        let eval_result = eval(&code_replaced);

        let value = eval_result.value;

        if success {
            match value.expect("expected successful evaluation on legal rename") {
                tvix_eval::Value::String(s) => {
                    assert_eq!(
                        "/nix/store/nd5z11x7zjqqz44rkbhc6v7yifdkn659-valid-name",
                        s.as_bstr()
                    );
                }
                v => panic!("unexpected value type: {:?}", v),
            }
        } else {
            assert!(value.is_none(), "unexpected success on illegal store paths");
        }
    }

    // Space is an illegal character.
    #[rstest]
    #[case(
        r#"(builtins.path { name = "valid-name"; path = @fixtures + "/te st"; recursive = false; })"#,
        true
    )]
    // Space is still an illegal character.
    #[case(
        r#"(builtins.path { name = "invalid name"; path = @fixtures + "/te st"; recursive = false; })"#,
        false
    )]
    // The non-recursive variant passes explicitly `recursive = false;`
    fn builtins_path_nonrecursive_rename(#[case] code: &str, #[case] success: bool) {
        // populate the fixtures dir
        let temp = TempDir::new().expect("create temporary directory");
        let p = temp.path().join("import_fixtures");

        // create the fixtures directory.
        // We produce them at runtime rather than shipping it inside the source
        // tree, as git can't model certain things - like directories without any
        // items.
        {
            fs::create_dir(&p).expect("creating import_fixtures");
            fs::write(p.join("te st"), "").expect("creating `/te st`");
        }
        // replace @fixtures with the temporary path containing the fixtures
        let code_replaced = code.replace("@fixtures", &p.to_string_lossy());

        let eval_result = eval(&code_replaced);

        let value = eval_result.value;

        if success {
            match value.expect("expected successful evaluation on legal rename") {
                tvix_eval::Value::String(s) => {
                    assert_eq!(
                        "/nix/store/il2rmfbqgs37rshr8w7x64hd4d3b4bsa-valid-name",
                        s.as_bstr()
                    );
                }
                v => panic!("unexpected value type: {:?}", v),
            }
        } else {
            assert!(value.is_none(), "unexpected success on illegal store paths");
        }
    }

    #[rstest]
    #[case(
        r#"(builtins.path { name = "valid-name"; path = @fixtures + "/te st"; recursive = false; sha256 = "sha256-47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU="; })"#,
        true
    )]
    #[case(
        r#"(builtins.path { name = "valid-name"; path = @fixtures + "/te st"; recursive = true; sha256 = "sha256-47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU="; })"#,
        false
    )]
    #[case(
        r#"(builtins.path { name = "valid-name"; path = @fixtures + "/te st"; recursive = true; sha256 = "sha256-d6xi4mKdjkX2JFicDIv5niSzpyI0m/Hnm8GGAIU04kY="; })"#,
        true
    )]
    #[case(
        r#"(builtins.path { name = "valid-name"; path = @fixtures + "/te st"; recursive = false; sha256 = "sha256-d6xi4mKdjkX2JFicDIv5niSzpyI0m/Hnm8GGAIU04kY="; })"#,
        false
    )]
    fn builtins_path_fod_locking(#[case] code: &str, #[case] exp_success: bool) {
        // populate the fixtures dir
        let temp = TempDir::new().expect("create temporary directory");
        let p = temp.path().join("import_fixtures");

        // create the fixtures directory.
        // We produce them at runtime rather than shipping it inside the source
        // tree, as git can't model certain things - like directories without any
        // items.
        {
            fs::create_dir(&p).expect("creating import_fixtures");
            fs::write(p.join("te st"), "").expect("creating `/te st`");
        }
        // replace @fixtures with the temporary path containing the fixtures
        let code_replaced = code.replace("@fixtures", &p.to_string_lossy());

        let eval_result = eval(&code_replaced);

        let value = eval_result.value;

        if exp_success {
            assert!(
                value.is_some(),
                "expected successful evaluation on legal rename and valid FOD sha256"
            );
        } else {
            assert!(value.is_none(), "unexpected success on invalid FOD sha256");
        }
    }

    #[rstest]
    #[case(
        r#"(builtins.path { name = "valid-path"; path = @fixtures + "/te st dir"; filter = _: _: true; })"#,
        "/nix/store/i28jmi4fwym4fw3flkrkp2mdxx50pdy0-valid-path"
    )]
    #[case(
        r#"(builtins.path { name = "valid-path"; path = @fixtures + "/te st dir"; filter = _: _: false; })"#,
        "/nix/store/pwza2ij9gk1fmzhbjnynmfv2mq2sgcap-valid-path"
    )]
    fn builtins_path_filter(#[case] code: &str, #[case] expected_outpath: &str) {
        // populate the fixtures dir
        let temp = TempDir::new().expect("create temporary directory");
        let p = temp.path().join("import_fixtures");

        // create the fixtures directory.
        // We produce them at runtime rather than shipping it inside the source
        // tree, as git can't model certain things - like directories without any
        // items.
        {
            fs::create_dir(&p).expect("creating import_fixtures");
            fs::create_dir(p.join("te st dir")).expect("creating `/te st dir`");
            fs::write(p.join("te st dir").join("test"), "").expect("creating `/te st dir/test`");
        }
        // replace @fixtures with the temporary path containing the fixtures
        let code_replaced = code.replace("@fixtures", &p.to_string_lossy());

        let eval_result = eval(&code_replaced);

        let value = eval_result.value.expect("must succeed");

        match value {
            tvix_eval::Value::String(s) => {
                assert_eq!(expected_outpath, s.as_bstr());
            }
            _ => panic!("unexpected value type: {:?}", value),
        }

        assert!(eval_result.errors.is_empty(), "errors should be empty");
    }

    // All tests filter out some unsupported (not representable in castore) nodes, confirming
    // invalid, but filtered-out nodes don't prevent ingestion of a path.
    #[rstest]
    #[cfg(target_family = "unix")]
    // There is a set of invalid filetypes.
    // We write various filter functions filtering them out, but usually leaving
    // some behind.
    // In case there's still invalid filetypes left after the filtering, we
    // expect the evaluation to fail.
    #[case::fail_kept_unknowns(
        r#"(builtins.filterSource (p: t: t == "unknown") @fixtures)"#,
        false
    )]
    // We filter all invalid filetypes, so the evaluation has to succeed.
    #[case::succeed_filter_unknowns(
        r#"(builtins.filterSource (p: t: t != "unknown") @fixtures)"#,
        true
    )]
    #[case::fail_kept_charnode(
        r#"(builtins.filterSource (p: t: (builtins.baseNameOf p) != "a_charnode") @fixtures)"#,
        false
    )]
    #[case::fail_kept_socket(
        r#"(builtins.filterSource (p: t: (builtins.baseNameOf p) != "a_socket") @fixtures)"#,
        false
    )]
    #[case::fail_kept_fifo(
        r#"(builtins.filterSource (p: t: (builtins.baseNameOf p) != "a_fifo") @fixtures)"#,
        false
    )]
    fn builtins_filter_source_unsupported_files(#[case] code: &str, #[case] exp_success: bool) {
        use nix::errno::Errno;
        use nix::sys::stat;
        use nix::unistd;
        use std::os::unix::net::UnixListener;
        use tempfile::TempDir;

        // We prepare a directory containing some unsupported file nodes:
        // - character device
        // - socket
        // - FIFO
        // and we run the evaluation inside that CWD.
        //
        // block devices cannot be tested because we don't have the right permissions.
        let temp = TempDir::with_prefix("foo").expect("Failed to create a temporary directory");

        // read, write, execute to the owner.
        unistd::mkfifo(&temp.path().join("a_fifo"), stat::Mode::S_IRWXU)
            .expect("Failed to create the FIFO");

        UnixListener::bind(temp.path().join("a_socket")).expect("Failed to create the socket");

        stat::mknod(
            &temp.path().join("a_charnode"),
            stat::SFlag::S_IFCHR,
            stat::Mode::S_IRWXU,
            0,
        )
        .inspect_err(|e| {
            if *e == Errno::EPERM {
                eprintln!(
                    "\
Missing permissions to create a character device node with mknod(2).
Please run this test as root or set CAP_MKNOD."
                );
            }
        })
        .expect("Failed to create a character device node");

        let code_replaced = code.replace("@fixtures", &temp.path().to_string_lossy());
        let eval_result = eval(&code_replaced);

        if exp_success {
            assert!(
                eval_result.value.is_some(),
                "unexpected failure on a directory of unsupported file types but all filtered: {:?}",
                eval_result.errors
            );
        } else {
            assert!(
                eval_result.value.is_none(),
                "unexpected success on unsupported file type ingestion: {:?}",
                eval_result.value
            );
        }
    }
}