use anyhow::{Result, anyhow};
use tokio::fs;
use std::path::{Path, PathBuf};
use ini::Ini;
use crate::util;
use crate::profile::Profile;

#[cfg(target_os = "linux")]
async fn symlink(src: impl AsRef<Path>, dst: impl AsRef<Path>) -> std::io::Result<()> {
    fs::symlink(src, dst).await
}

#[cfg(target_os = "windows")]
async fn symlink(src: impl AsRef<Path>, dst: impl AsRef<Path>) -> std::io::Result<()> {
    //std::os::windows::fs::junction_point(src, dst) // is unstable
    junction::create(src, dst)
}

pub async fn line_up(p: &Profile, pkg_hash: String) -> Result<()> {
    let dir_out = p.dir();

    if dir_out.join("option").exists() {
        fs::remove_dir_all(dir_out.join("option")).await?;
    }

    fs::create_dir_all(dir_out.join("option")).await?;

    let hash_path = p.dir().join(".sl-state");
    let prev_hash = fs::read_to_string(&hash_path).await.unwrap_or_default();
    if prev_hash != pkg_hash {
        log::debug!("state {} -> {}", prev_hash, pkg_hash);
        fs::write(hash_path, pkg_hash).await
            .map_err(|e| anyhow!("Unable to write the state file: {}", e))?;
        prepare_packages(p).await?;
    }

    prepare_config(p).await?;

    Ok(())
}

async fn prepare_packages(p: &Profile) -> Result<()> {
    let dir_out = p.dir();

    if dir_out.join("BepInEx").exists() {
        fs::remove_dir_all(dir_out.join("BepInEx")).await?;
    }

    for m in &p.mods {
        log::debug!("Preparing {}", m);
        let (namespace, name) = m.0.split_at(m.0.find("-").expect("Invalid mod definition"));
        let bpx_dir = util::pkg_dir_of(namespace, &name[1..]) // cut the hyphen
            .join("app")
            .join("BepInEx");
        if bpx_dir.exists() {
            util::copy_recursive(&bpx_dir, &dir_out.join("BepInEx"))?;
        }

        let opt_dir = util::pkg_dir_of(namespace, &name[1..]).join("option");
        if opt_dir.exists() {
            let x = opt_dir.read_dir().unwrap().next().unwrap()?;
            if x.metadata()?.is_dir() {
                symlink(&x.path(), &dir_out.join("option").join(x.file_name())).await?;
            }
        }
    }

    Ok(())
}

pub async fn prepare_config(p: &Profile) -> Result<()> {
    let dir_out = p.dir();

    let ini_in_raw = fs::read_to_string(p.exe_dir.join("segatools.ini")).await?;
    let ini_in = Ini::load_from_str(&ini_in_raw)?;
    let mut opt_dir_in = PathBuf::from(
        ini_in.section(Some("vfs"))
            .ok_or_else(|| anyhow!("No VFS section in segatools.ini"))?
            .get("option")
            .ok_or_else(|| anyhow!("No option specified in segatools.ini"))?
    );
    if opt_dir_in.is_relative() {
        opt_dir_in = p.exe_dir.join(opt_dir_in);
    }
    let opt_dir_out = &dir_out.join("option");

    let mut ini_out = ini_in.clone();
    ini_out.with_section(Some("vfs")).set(
        "option",
        util::path_to_str(opt_dir_out)?
    );
    ini_out.with_section(Some("unity"))
        .set("enable", "1")
        .set(
            "targetAssembly",
            util::path_to_str(dir_out.join("BepInEx").join("core").join("BepInEx.Preloader.dll"))?
        );

    if p.get_bool("aime", false) {
        ini_out.with_section(Some("aime"))
            .set("enable", "1")
            .set("aimePath", util::path_to_str(dir_out.join("aime.txt"))?);
    }

    ini_out.write_to_file(dir_out.join("segatools.ini"))?;

    log::debug!("Option dir: {} -> {}", opt_dir_in.to_string_lossy(), opt_dir_out.to_string_lossy());
    for opt in opt_dir_in.read_dir()? {
        let opt = opt?;
        symlink(&opt.path(), opt_dir_out.join(opt.file_name())).await?;
    }

    Ok(())
}