use std::{
    fs::{self, File},
    io::{BufReader, Cursor, Read, Write},
    path::{Path, PathBuf},
};

use flate2::read::GzDecoder;
use tar::Archive;
use zip::write::FileOptions;

macro_rules! p {
    ($($tokens: tt)*) => {
        println!("cargo:warning={}", format!($($tokens)*))
    }
}

/// get cargo features to compile packages with
fn get_features() -> String {
    let mut features = "".to_string();
    for (key, _) in std::env::vars() {
        if key.starts_with("CARGO_FEATURE_") {
            let feature = key
                .trim_start_matches("CARGO_FEATURE_")
                .to_lowercase()
                .replace("_", "-");
            features.push_str(&feature);
        }
    }
    features
}

/// print `cargo:rerun-if-changed=PATH` for each path of interest
fn output_reruns(dir: &Path) {
    // Check files individually
    if let Ok(entries) = fs::read_dir(dir) {
        for entry in entries.filter_map(|e| e.ok()) {
            let path = entry.path();
            if path.is_dir() {
                if let Some(dirname) = path.file_name().and_then(|n| n.to_str()) {
                    if dirname == "ui" || dirname == "target" {
                        // do not prompt a rerun if only UI/build files have changed
                        continue;
                    }
                    // If the entry is a directory not in rerun_files, recursively walk it
                    output_reruns(&path);
                }
            } else {
                if let Some(filename) = path.file_name().and_then(|n| n.to_str()) {
                    if filename.ends_with(".zip") || filename.ends_with(".wasm") {
                        // do not prompt a rerun for compiled outputs
                        continue;
                    }
                    // any other changed file within a package subdir prompts a rerun
                    println!("cargo::rerun-if-changed={}", path.display());
                }
            }
        }
    }
}

fn _untar_gz_file(path: &Path, dest: &Path) -> std::io::Result<()> {
    // Open the .tar.gz file
    let tar_gz = File::open(path)?;
    let tar_gz_reader = BufReader::new(tar_gz);

    // Decode the gzip layer
    let tar = GzDecoder::new(tar_gz_reader);

    // Create a new archive from the tar file
    let mut archive = Archive::new(tar);

    // Unpack the archive into the specified destination directory
    archive.unpack(dest)?;

    Ok(())
}

fn build_and_zip_package(
    entry_path: PathBuf,
    parent_pkg_path: &str,
    features: &str,
) -> anyhow::Result<(String, String, Vec<u8>)> {
    let rt = tokio::runtime::Runtime::new().unwrap();
    rt.block_on(async {
        kit::build::execute(
            &entry_path,
            true,
            false,
            true,
            features,
            None,
            None,
            None,
            vec![],
            vec![],
            false,
            false,
            false,
        )
        .await
        .map_err(|e| anyhow::anyhow!("{:?}", e))?;

        let mut writer = Cursor::new(Vec::new());
        let options = FileOptions::default()
            .compression_method(zip::CompressionMethod::Deflated)
            .unix_permissions(0o755)
            .last_modified_time(zip::DateTime::from_date_and_time(2023, 6, 19, 0, 0, 0).unwrap());
        {
            let mut zip = zip::ZipWriter::new(&mut writer);

            for sub_entry in walkdir::WalkDir::new(parent_pkg_path) {
                let sub_entry = sub_entry?;
                let path = sub_entry.path();
                let name = path.strip_prefix(Path::new(parent_pkg_path))?;

                if path.is_file() {
                    zip.start_file(name.to_string_lossy(), options)?;
                    let mut file = File::open(path)?;
                    let mut buffer = Vec::new();
                    file.read_to_end(&mut buffer)?;
                    zip.write_all(&buffer)?;
                } else if !name.as_os_str().is_empty() {
                    zip.add_directory(name.to_string_lossy(), options)?;
                }
            }
            zip.finish()?;
        }

        let zip_contents = writer.into_inner();
        let zip_filename = format!("{}.zip", entry_path.file_name().unwrap().to_str().unwrap());
        Ok((entry_path.display().to_string(), zip_filename, zip_contents))
    })
}

fn main() -> anyhow::Result<()> {
    if std::env::var("SKIP_BUILD_SCRIPT").is_ok() {
        p!("skipping build script");
        return Ok(());
    }

    let pwd = std::env::current_dir()?;
    let parent_dir = pwd.parent().unwrap();
    let packages_dir = pwd.join("packages");

    if std::env::var("SKIP_BUILD_FRONTEND").is_ok() {
        p!("skipping frontend builds");
    } else {
        // build core frontends
        let core_frontends = vec![
            "src/register-ui",
            "packages/app_store/ui",
            "packages/homepage/ui",
            // chess when brought in
        ];

        // for each frontend, execute build.sh
        for frontend in core_frontends {
            let status = std::process::Command::new("sh")
                .current_dir(pwd.join(frontend))
                .arg("./build.sh")
                .status()?;
            if !status.success() {
                return Err(anyhow::anyhow!("Failed to build frontend: {}", frontend));
            }
        }
    }

    output_reruns(&packages_dir);

    let features = get_features();

    let results: Vec<anyhow::Result<(String, String, Vec<u8>)>> = fs::read_dir(&packages_dir)?
        .filter_map(|entry| {
            let entry_path = match entry {
                Ok(e) => e.path(),
                Err(_) => return None,
            };
            let child_pkg_path = entry_path.join("pkg");
            if !child_pkg_path.exists() {
                // don't run on, e.g., `.DS_Store`
                return None;
            }
            Some(build_and_zip_package(
                entry_path.clone(),
                child_pkg_path.to_str().unwrap(),
                &features,
            ))
        })
        .collect();

    // Process results, e.g., write to `bootstrapped_processes.rs`
    // This part remains sequential
    let mut bootstrapped_processes = vec![];
    writeln!(
        bootstrapped_processes,
        "pub static BOOTSTRAPPED_PROCESSES: &[(&str, &[u8], &[u8])] = &["
    )?;

    for result in results {
        match result {
            Ok((entry_path, zip_filename, zip_contents)) => {
                // Further processing, like saving ZIP files and updating bootstrapped_processes
                let metadata_path = format!("{}/metadata.json", entry_path);
                let zip_path = format!("{}/target/{}", parent_dir.display(), zip_filename);
                fs::write(&zip_path, &zip_contents)?;

                writeln!(
                    bootstrapped_processes,
                    "    (\"{}\", include_bytes!(\"{}\"), include_bytes!(\"{}\")),",
                    zip_filename, metadata_path, zip_path,
                )?;
            }
            Err(e) => return Err(e),
        }
    }

    writeln!(bootstrapped_processes, "];")?;
    let target_dir = pwd.join("../target");
    if !target_dir.exists() {
        fs::create_dir_all(&target_dir)?;
    }
    let bootstrapped_processes_path = target_dir.join("bootstrapped_processes.rs");
    fs::write(&bootstrapped_processes_path, bootstrapped_processes)?;

    let version = if let Ok(version) = std::env::var("DOCKER_BUILD_IMAGE_VERSION") {
        // embed the DOCKER_BUILD_IMAGE_VERSION
        version
    } else {
        "none".to_string()
    };
    println!("cargo:rustc-env=DOCKER_BUILD_IMAGE_VERSION={version}");

    Ok(())
}