use crate::nixhash::CAHash;
use crate::store_path::StorePathRef;
use crate::{derivation::OutputError, store_path::StorePath};
use serde::de::Unexpected;
use serde::{Deserialize, Serialize};
use serde_json::Map;
use std::borrow::Cow;

/// References the derivation output.
#[derive(Clone, Debug, Default, Eq, PartialEq, Serialize)]
pub struct Output {
    /// Store path of build result.
    pub path: Option<StorePath>,

    #[serde(flatten)]
    pub ca_hash: Option<CAHash>, // we can only represent a subset here.
}

impl<'de> Deserialize<'de> for Output {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
        let fields = Map::deserialize(deserializer)?;
        let path: &str = fields
            .get("path")
            .ok_or(serde::de::Error::missing_field(
                "`path` is missing but required for outputs",
            ))?
            .as_str()
            .ok_or(serde::de::Error::invalid_type(
                serde::de::Unexpected::Other("certainly not a string"),
                &"a string",
            ))?;

        let path = StorePathRef::from_absolute_path(path.as_bytes())
            .map_err(|_| serde::de::Error::invalid_value(Unexpected::Str(path), &"StorePath"))?;
        Ok(Self {
            path: Some(path.to_owned()),
            ca_hash: CAHash::from_map::<D>(&fields)?,
        })
    }
}

impl Output {
    pub fn is_fixed(&self) -> bool {
        self.ca_hash.is_some()
    }

    /// The output path as a string -- use `""` to indicate an unset output path.
    pub fn path_str(&self) -> Cow<str> {
        match &self.path {
            None => Cow::Borrowed(""),
            Some(path) => Cow::Owned(path.to_absolute_path()),
        }
    }

    pub fn validate(&self, validate_output_paths: bool) -> Result<(), OutputError> {
        if let Some(fixed_output_hash) = &self.ca_hash {
            match fixed_output_hash {
                CAHash::Flat(_) | CAHash::Nar(_) => {
                    // all hashes allowed for Flat, and Nar.
                }
                _ => return Err(OutputError::InvalidCAHash(fixed_output_hash.clone())),
            }
        }

        if validate_output_paths && self.path.is_none() {
            return Err(OutputError::MissingOutputPath);
        }
        Ok(())
    }
}

/// This ensures that a potentially valid input addressed
/// output is deserialized as a non-fixed output.
#[test]
fn deserialize_valid_input_addressed_output() {
    let json_bytes = r#"
    {
      "path": "/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432"
    }"#;
    let output: Output = serde_json::from_str(json_bytes).expect("must parse");

    assert!(!output.is_fixed());
}

/// This ensures that a potentially valid fixed output
/// output deserializes fine as a fixed output.
#[test]
fn deserialize_valid_fixed_output() {
    let json_bytes = r#"
    {
        "path": "/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432",
        "hash": "08813cbee9903c62be4c5027726a418a300da4500b2d369d3af9286f4815ceba",
        "hashAlgo": "r:sha256"
    }"#;
    let output: Output = serde_json::from_str(json_bytes).expect("must parse");

    assert!(output.is_fixed());
}

/// This ensures that parsing an input with the invalid hash encoding
/// will result in a parsing failure.
#[test]
fn deserialize_with_error_invalid_hash_encoding_fixed_output() {
    let json_bytes = r#"
    {
        "path": "/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432",
        "hash": "IAMNOTVALIDNIXBASE32",
        "hashAlgo": "r:sha256"
    }"#;
    let output: Result<Output, _> = serde_json::from_str(json_bytes);

    assert!(output.is_err());
}

/// This ensures that parsing an input with the wrong hash algo
/// will result in a parsing failure.
#[test]
fn deserialize_with_error_invalid_hash_algo_fixed_output() {
    let json_bytes = r#"
    {
        "path": "/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432",
        "hash": "08813cbee9903c62be4c5027726a418a300da4500b2d369d3af9286f4815ceba",
        "hashAlgo": "r:sha1024"
    }"#;
    let output: Result<Output, _> = serde_json::from_str(json_bytes);

    assert!(output.is_err());
}

/// This ensures that parsing an input with the missing hash algo but present hash will result in a
/// parsing failure.
#[test]
fn deserialize_with_error_missing_hash_algo_fixed_output() {
    let json_bytes = r#"
    {
        "path": "/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432",
        "hash": "08813cbee9903c62be4c5027726a418a300da4500b2d369d3af9286f4815ceba",
    }"#;
    let output: Result<Output, _> = serde_json::from_str(json_bytes);

    assert!(output.is_err());
}

/// This ensures that parsing an input with the missing hash but present hash algo will result in a
/// parsing failure.
#[test]
fn deserialize_with_error_missing_hash_fixed_output() {
    let json_bytes = r#"
    {
        "path": "/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432",
        "hashAlgo": "r:sha1024"
    }"#;
    let output: Result<Output, _> = serde_json::from_str(json_bytes);

    assert!(output.is_err());
}

#[test]
fn serialize_deserialize() {
    let json_bytes = r#"
    {
      "path": "/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432"
    }"#;
    let output: Output = serde_json::from_str(json_bytes).expect("must parse");

    let s = serde_json::to_string(&output).expect("Serialize");
    let output2: Output = serde_json::from_str(&s).expect("must parse again");

    assert_eq!(output, output2);
}

#[test]
fn serialize_deserialize_fixed() {
    let json_bytes = r#"
    {
        "path": "/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432",
        "hash": "08813cbee9903c62be4c5027726a418a300da4500b2d369d3af9286f4815ceba",
        "hashAlgo": "r:sha256"
    }"#;
    let output: Output = serde_json::from_str(json_bytes).expect("must parse");

    let s = serde_json::to_string_pretty(&output).expect("Serialize");
    let output2: Output = serde_json::from_str(&s).expect("must parse again");

    assert_eq!(output, output2);
}