use std::{collections::HashMap, path::PathBuf, rc::Rc};

use smol_str::SmolStr;
use std::fmt::Write;
use tracing::{instrument, Span};
use tracing_indicatif::span_ext::IndicatifSpanExt;
use tvix_build::buildservice;
use tvix_eval::{
    builtins::impure_builtins,
    observer::{DisassemblingObserver, TracingObserver},
    ErrorKind, EvalIO, Value,
};
use tvix_glue::{
    builtins::{add_derivation_builtins, add_fetcher_builtins, add_import_builtins},
    configure_nix_path,
    tvix_io::TvixIO,
    tvix_store_io::TvixStoreIO,
};

pub mod args;
pub mod assignment;
pub mod repl;

pub use args::Args;
pub use repl::Repl;

pub fn init_io_handle(tokio_runtime: &tokio::runtime::Runtime, args: &Args) -> Rc<TvixStoreIO> {
    let (blob_service, directory_service, path_info_service, nar_calculation_service) =
        tokio_runtime
            .block_on({
                let blob_service_addr = args.blob_service_addr.clone();
                let directory_service_addr = args.directory_service_addr.clone();
                let path_info_service_addr = args.path_info_service_addr.clone();
                async move {
                    tvix_store::utils::construct_services(
                        blob_service_addr,
                        directory_service_addr,
                        path_info_service_addr,
                    )
                    .await
                }
            })
            .expect("unable to setup {blob|directory|pathinfo}service before interpreter setup");

    let build_service = tokio_runtime
        .block_on({
            let blob_service = blob_service.clone();
            let directory_service = directory_service.clone();
            async move {
                buildservice::from_addr(
                    &args.build_service_addr,
                    blob_service.clone(),
                    directory_service.clone(),
                )
                .await
            }
        })
        .expect("unable to setup buildservice before interpreter setup");

    Rc::new(TvixStoreIO::new(
        blob_service.clone(),
        directory_service.clone(),
        path_info_service.into(),
        nar_calculation_service.into(),
        build_service.into(),
        tokio_runtime.handle().clone(),
    ))
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum AllowIncomplete {
    Allow,
    #[default]
    RequireComplete,
}

impl AllowIncomplete {
    fn allow(&self) -> bool {
        matches!(self, Self::Allow)
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct IncompleteInput;

/// Interprets the given code snippet, printing out warnings and errors and returning the result
pub fn evaluate(
    tvix_store_io: Rc<TvixStoreIO>,
    code: &str,
    path: Option<PathBuf>,
    args: &Args,
    allow_incomplete: AllowIncomplete,
    env: Option<&HashMap<SmolStr, Value>>,
) -> Result<Option<Value>, IncompleteInput> {
    let span = Span::current();
    span.pb_start();
    span.pb_set_style(&tvix_tracing::PB_SPINNER_STYLE);
    span.pb_set_message("Setting up evaluator…");

    let mut eval_builder = tvix_eval::Evaluation::builder(Box::new(TvixIO::new(
        tvix_store_io.clone() as Rc<dyn EvalIO>,
    )) as Box<dyn EvalIO>)
    .enable_import()
    .with_strict(args.strict)
    .add_builtins(impure_builtins())
    .env(env);

    eval_builder = add_derivation_builtins(eval_builder, Rc::clone(&tvix_store_io));
    eval_builder = add_fetcher_builtins(eval_builder, Rc::clone(&tvix_store_io));
    eval_builder = add_import_builtins(eval_builder, tvix_store_io);
    eval_builder = configure_nix_path(eval_builder, &args.nix_search_path);

    let source_map = eval_builder.source_map().clone();
    let result = {
        let mut compiler_observer =
            DisassemblingObserver::new(source_map.clone(), std::io::stderr());
        if args.dump_bytecode {
            eval_builder.set_compiler_observer(Some(&mut compiler_observer));
        }

        let mut runtime_observer = TracingObserver::new(std::io::stderr());
        if args.trace_runtime {
            if args.trace_runtime_timing {
                runtime_observer.enable_timing()
            }
            eval_builder.set_runtime_observer(Some(&mut runtime_observer));
        }

        span.pb_set_message("Evaluating…");

        let eval = eval_builder.build();
        eval.evaluate(code, path)
    };

    if allow_incomplete.allow()
        && result.errors.iter().any(|err| {
            matches!(
                &err.kind,
                ErrorKind::ParseErrors(pes)
                    if pes.iter().any(|pe| matches!(pe, rnix::parser::ParseError::UnexpectedEOF))
            )
        })
    {
        return Err(IncompleteInput);
    }

    if args.display_ast {
        if let Some(ref expr) = result.expr {
            eprintln!("AST: {}", tvix_eval::pretty_print_expr(expr));
        }
    }

    for error in &result.errors {
        error.fancy_format_stderr();
    }

    if !args.no_warnings {
        for warning in &result.warnings {
            warning.fancy_format_stderr(&source_map);
        }
    }

    Ok(result.value)
}

pub struct InterpretResult {
    output: String,
    success: bool,
}

impl InterpretResult {
    pub fn empty_success() -> Self {
        Self {
            output: String::new(),
            success: true,
        }
    }

    pub fn finalize(self) -> bool {
        print!("{}", self.output);
        self.success
    }

    pub fn output(&self) -> &str {
        &self.output
    }

    pub fn success(&self) -> bool {
        self.success
    }
}

/// Interprets the given code snippet, printing out warnings, errors
/// and the result itself. The return value indicates whether
/// evaluation succeeded.
#[instrument(skip_all, fields(indicatif.pb_show=1))]
pub fn interpret(
    tvix_store_io: Rc<TvixStoreIO>,
    code: &str,
    path: Option<PathBuf>,
    args: &Args,
    explain: bool,
    allow_incomplete: AllowIncomplete,
    env: Option<&HashMap<SmolStr, Value>>,
) -> Result<InterpretResult, IncompleteInput> {
    let mut output = String::new();
    let result = evaluate(tvix_store_io, code, path, args, allow_incomplete, env)?;

    if let Some(value) = result.as_ref() {
        if explain {
            writeln!(&mut output, "=> {}", value.explain()).unwrap();
        } else if args.raw {
            writeln!(&mut output, "{}", value.to_contextful_str().unwrap()).unwrap();
        } else {
            writeln!(&mut output, "=> {} :: {}", value, value.type_of()).unwrap();
        }
    }

    // inform the caller about any errors
    Ok(InterpretResult {
        output,
        success: result.is_some(),
    })
}