use chrono::{DateTime, Local};
use collections::{BTreeSet, HashMap};
use serde_json_lenient::Value;
use std::{path::Path, sync::Arc};

#[derive(Clone, Debug)]
pub struct PackageJson {
    pub mtime: DateTime<Local>,
    pub data: PackageJsonData,
}

#[derive(Clone, Debug, Default, PartialEq, Eq)]
pub struct PackageJsonData {
    pub jest_package_path: Option<Arc<Path>>,
    pub mocha_package_path: Option<Arc<Path>>,
    pub vitest_package_path: Option<Arc<Path>>,
    pub jasmine_package_path: Option<Arc<Path>>,
    pub bun_package_path: Option<Arc<Path>>,
    pub node_package_path: Option<Arc<Path>>,
    pub scripts: BTreeSet<(Arc<Path>, String)>,
    pub package_manager: Option<&'static str>,
}

impl PackageJsonData {
    pub fn new(path: Arc<Path>, package_json: HashMap<String, Value>) -> Self {
        let mut scripts = BTreeSet::new();
        if let Some(Value::Object(package_json_scripts)) = package_json.get("scripts") {
            scripts.extend(
                package_json_scripts
                    .keys()
                    .cloned()
                    .map(|name| (path.clone(), name)),
            );
        }

        let mut jest_package_path = None;
        let mut mocha_package_path = None;
        let mut vitest_package_path = None;
        let mut jasmine_package_path = None;
        let mut bun_package_path = None;
        let mut node_package_path = None;
        if let Some(Value::Object(dependencies)) = package_json.get("devDependencies") {
            if dependencies.contains_key("jest") {
                jest_package_path.get_or_insert_with(|| path.clone());
            }
            if dependencies.contains_key("mocha") {
                mocha_package_path.get_or_insert_with(|| path.clone());
            }
            if dependencies.contains_key("vitest") {
                vitest_package_path.get_or_insert_with(|| path.clone());
            }
            if dependencies.contains_key("jasmine") {
                jasmine_package_path.get_or_insert_with(|| path.clone());
            }
            if dependencies.contains_key("@types/bun") {
                bun_package_path.get_or_insert_with(|| path.clone());
            }
            if dependencies.contains_key("@types/node") {
                node_package_path.get_or_insert_with(|| path.clone());
            }
        }
        if let Some(Value::Object(dev_dependencies)) = package_json.get("dependencies") {
            if dev_dependencies.contains_key("jest") {
                jest_package_path.get_or_insert_with(|| path.clone());
            }
            if dev_dependencies.contains_key("mocha") {
                mocha_package_path.get_or_insert_with(|| path.clone());
            }
            if dev_dependencies.contains_key("vitest") {
                vitest_package_path.get_or_insert_with(|| path.clone());
            }
            if dev_dependencies.contains_key("jasmine") {
                jasmine_package_path.get_or_insert_with(|| path.clone());
            }
            if dev_dependencies.contains_key("@types/bun") {
                bun_package_path.get_or_insert_with(|| path.clone());
            }
            if dev_dependencies.contains_key("@types/node") {
                node_package_path.get_or_insert_with(|| path.clone());
            }
        }

        let package_manager = package_manager_from_package_json(&package_json);

        Self {
            jest_package_path,
            mocha_package_path,
            vitest_package_path,
            jasmine_package_path,
            bun_package_path,
            node_package_path,
            scripts,
            package_manager,
        }
    }

    pub fn merge(&mut self, other: Self) {
        self.jest_package_path = self.jest_package_path.take().or(other.jest_package_path);
        self.mocha_package_path = self.mocha_package_path.take().or(other.mocha_package_path);
        self.vitest_package_path = self
            .vitest_package_path
            .take()
            .or(other.vitest_package_path);
        self.jasmine_package_path = self
            .jasmine_package_path
            .take()
            .or(other.jasmine_package_path);
        self.bun_package_path = self.bun_package_path.take().or(other.bun_package_path);
        self.node_package_path = self.node_package_path.take().or(other.node_package_path);
        self.scripts.extend(other.scripts);
        self.package_manager = self.package_manager.or(other.package_manager);
    }
}

fn package_manager_from_package_json(
    package_json: &HashMap<String, Value>,
) -> Option<&'static str> {
    package_json
        .get("packageManager")
        .and_then(|value| value.as_str())
        .and_then(package_manager_name)
        .or_else(|| {
            package_json
                .get("devEngines")
                .and_then(|value| value.as_object())
                .and_then(|dev_engines| dev_engines.get("packageManager"))
                .and_then(package_manager_from_dev_engine)
        })
}

fn package_manager_from_dev_engine(value: &Value) -> Option<&'static str> {
    match value {
        Value::Object(package_manager) => package_manager
            .get("name")
            .and_then(|name| name.as_str())
            .and_then(package_manager_name),
        Value::Array(package_managers) => package_managers
            .iter()
            .find_map(package_manager_from_dev_engine),
        _ => None,
    }
}

fn package_manager_name(value: &str) -> Option<&'static str> {
    let value = value.split_once('@').map(|(name, _)| name).unwrap_or(value);
    match value {
        "pnpm" => Some("pnpm"),
        "yarn" => Some("yarn"),
        "npm" => Some("npm"),
        "bun" => Some("bun"),
        _ => None,
    }
}

#[cfg(test)]
mod tests {
    use std::path::Path;

    use super::PackageJsonData;

    #[test]
    fn package_manager_detection() {
        fn package_manager(source: &str) -> Option<&'static str> {
            PackageJsonData::new(
                Path::new("/root/package.json").into(),
                serde_json_lenient::from_str(source).expect("provided source should be valid JSON"),
            )
            .package_manager
        }

        assert_eq!(
            package_manager(r#"{"packageManager": "pnpm@11.1.3"}"#),
            Some("pnpm")
        );

        assert_eq!(
            package_manager(
                r#"{"devEngines": {"packageManager": {"name": "pnpm", "version": "^11.1.3", "onFail": "download"}}}"#
            ),
            Some("pnpm"),
        );

        assert_eq!(
            package_manager(
                r#"{"devEngines": {"packageManager": [{"name": "foo"}, {"name": "yarn", "version": "^4.0.0"}]}}"#
            ),
            Some("yarn"),
        );

        assert_eq!(
            package_manager(
                r#"{"packageManager": "npm@10.0.0", "devEngines": {"packageManager": {"name": "pnpm"}}}"#
            ),
            Some("npm"),
        );

        assert_eq!(
            package_manager(r#"{"devEngines": {"packageManager": {"version": "^11.1.3"}}}"#),
            None,
        );
    }
}