//! 封面 Python 运行时定位（bundled `resources/pythonruntime/python.exe`）
//! 封面脚本由服务端下发，不在此目录打包。

use std::collections::HashMap;
use std::path::{Path, PathBuf};

fn exe_name() -> &'static str {
    if cfg!(windows) {
        "python.exe"
    } else {
        "python3"
    }
}

fn pythonruntime_candidates() -> Vec<PathBuf> {
    let mut out = Vec::new();
    // 开发源码树优先：target/debug/resources 可能是残缺副本（缺 PIL 等）
    out.push(
        PathBuf::from("src-tauri/resources/pythonruntime").join(exe_name()),
    );
    out.push(PathBuf::from("resources/pythonruntime").join(exe_name()));
    if let Ok(exe) = std::env::current_exe() {
        if let Some(dir) = exe.parent() {
            out.push(
                dir.join("resources")
                    .join("pythonruntime")
                    .join(exe_name()),
            );
        }
    }
    out
}

/// `python.exe` 所在目录即 PYTHONHOME（含 Lib/site-packages）。
pub fn python_home(python_exe: &Path) -> PathBuf {
    python_exe
        .parent()
        .map(|p| p.to_path_buf())
        .unwrap_or_else(|| PathBuf::from("."))
}

fn site_packages_dir(python_exe: &Path) -> PathBuf {
    python_home(python_exe).join("Lib").join("site-packages")
}

fn runtime_has_pillow(python_exe: &Path) -> bool {
    let site = site_packages_dir(python_exe);
    site.join("PIL").is_dir() || site.join("Pillow").is_dir()
}

/// bundled `resources/pythonruntime/python.exe` 或 `AICLIENT_PYTHON_PATH`。
pub fn locate_python() -> Option<PathBuf> {
    if let Ok(p) = std::env::var("AICLIENT_PYTHON_PATH") {
        let pb = PathBuf::from(&p);
        if pb.is_file() {
            return Some(pb);
        }
    }
    for path in pythonruntime_candidates() {
        if path.is_file() && runtime_has_pillow(&path) {
            return Some(path);
        }
    }
    for path in pythonruntime_candidates() {
        if path.is_file() {
            return Some(path);
        }
    }
    None
}

/// 为 bundled Python 子进程设置 PYTHONHOME / PYTHONPATH（否则找不到 PIL/cv2）。
pub fn apply_python_runtime_env(
    env: &mut HashMap<String, String>,
    python_exe: &Path,
    bundle_dir: Option<&Path>,
) {
    let home = python_home(python_exe);
    env.insert(
        "PYTHONHOME".into(),
        home.to_string_lossy().into_owned(),
    );
    let site = site_packages_dir(python_exe);
    let sep = if cfg!(windows) { ";" } else { ":" };
    let mut paths = vec![site.to_string_lossy().into_owned()];
    if let Some(dir) = bundle_dir {
        paths.push(dir.to_string_lossy().into_owned());
    }
    env.insert("PYTHONPATH".into(), paths.join(sep));
    env.remove("PYTHONUSERBASE");
    env.insert("PYTHONNOUSERSITE".into(), "1".into());
    env.insert(
        "AICLIENT_PYTHON_HOME".into(),
        home.to_string_lossy().into_owned(),
    );
}

/// 开发期本地脚本目录（发布构建由服务端拉取，不依赖此路径）。
pub fn locate_cover_scripts_dir() -> Option<PathBuf> {
    if let Ok(p) = std::env::var("AICLIENT_COVER_SCRIPTS_DIR") {
        let pb = PathBuf::from(&p);
        if pb.join("advanced_cover_generator.py").is_file() {
            return Some(pb);
        }
    }
    let backend = PathBuf::from("../pythonbackend/scripts/cover");
    if backend.join("advanced_cover_generator.py").is_file() {
        return backend.canonicalize().ok();
    }
    None
}

/// 将 ffmpeg 所在目录 prepend 到 PATH（供 Python 子进程调用 ffmpeg）。
pub fn prepend_ffmpeg_to_path(env_path: &str) -> String {
    let sep = if cfg!(windows) { ";" } else { ":" };
    if let Some(ffmpeg) = crate::ffmpeg::locate_ffmpeg() {
        if let Some(dir) = ffmpeg.parent() {
            return format!("{}{}{}", dir.display(), sep, env_path);
        }
    }
    env_path.to_string()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn pythonruntime_dev_path() {
        let dev = PathBuf::from("src-tauri/resources/pythonruntime/python.exe");
        if dev.is_file() {
            assert!(locate_python().is_some());
        }
    }
}