//! See <https://github.com/matklad/cargo-xtask/>.
//!
//! This binary defines various auxiliary build commands, which are not
//! expressible with just `cargo`.
//!
//! This binary is integrated into the `cargo` command line by using an alias in
//! `.cargo/config`.

use std::{fs::File, io::Write, process::Command};
use std::{
    io::{BufReader, BufWriter, Read},
    path::{Path, PathBuf},
};

use anyhow::{anyhow, bail, ensure, Context, Result};
use build_info::BuildInfo;
use clap::{Parser, Subcommand, ValueEnum};
use flate2::{write::GzEncoder, Compression};
use once_cell::sync::Lazy;
use semver::{Prerelease, Version};
use tar::Builder;

const PKG_NAME: &str = "projectr";
const PKG_VER: &str = env!("CARGO_PKG_VERSION");
const PKG_INCLUDE: &[&str] = &[
    "bin/tmux-projectr",
    "CONTRIBUTING.md",
    "README.md",
    "LICENSE",
];

fn main() -> Result<()> {
    let cli = Cli::parse();

    match cli.command {
        Commands::OutDir => println!("{}", out_dir()?.display()),
        Commands::Version => match version(cli.force) {
            Ok(v) => println!("{v}"),
            Err(_) => std::process::exit(1),
        },
        Commands::Dist => {
            let version = version(cli.force)?;
            let targz = generate_tar_gz(version)?;
            println!("{}", targz.display());
        }
        Commands::Bump { level, pre_release } => {
            let prev = version(cli.force)?;
            let next = bump(prev, level, pre_release)?;
            println!("{next}");
        }
    };

    Ok(())
}

#[derive(Debug, Clone, Parser)]
#[command(author, version, about)]
struct Cli {
    /// Disable version/git tag check
    #[arg(short, long, global = true)]
    force: bool,

    #[command(subcommand)]
    command: Commands,
}

#[derive(Debug, Clone, Subcommand)]
enum Commands {
    /// Print the default value of OUT_DIR used by cargo when building the package.
    OutDir,

    /// Validate a git tag matching the package version exists and print version.
    Version,

    /// Generate distributable package.
    Dist,

    /// Bump the version and update version dependant locations in files.
    Bump {
        /// SemVer field to increment.
        #[arg(value_enum, required = false)]
        level: Level,
        /// Set pre-release field.
        #[arg(short, long)]
        pre_release: Option<Prerelease>,
    },
}

#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, PartialOrd, Ord, ValueEnum)]
pub enum Level {
    Major,
    Minor,
    #[default]
    Patch,
}

impl std::str::FromStr for Level {
    type Err = anyhow::Error;

    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
        match s.to_lowercase().as_str() {
            "major" => Ok(Level::Major),
            "minor" => Ok(Level::Minor),
            "patch" => Ok(Level::Patch),
            s => Err(anyhow::anyhow!("Invalid bump level: {s}")),
        }
    }
}

fn version(force: bool) -> Result<Version> {
    use build_info::VersionControl::Git;

    let version: Version = PKG_VER.parse()?;

    let BuildInfo {
        version_control: Some(Git(git)),
        ..
    } = build_info() else {
        bail!("Failed to get version control info.");
    };

    if force || git.tags.contains(&format!("v{version}")) {
        Ok(version)
    } else {
        Err(anyhow!("Failed to find git tag matching package version."))
    }
}

fn out_dir() -> Result<PathBuf> {
    RELEASE_DIR
        .join("build")
        .read_dir()
        .context("Failed to read build directory.")?
        .flatten()
        .filter_map(|d| {
            d.file_name()
                .to_str()?
                .starts_with(PKG_NAME)
                .then(|| d.path().join("invoked.timestamp"))
                .filter(|p| p.exists())
        })
        .reduce(|acc, path_buf| {
            std::cmp::max_by_key(path_buf, acc, |p| {
                p.metadata()
                    .and_then(|m| m.modified())
                    .unwrap_or(std::time::SystemTime::UNIX_EPOCH)
            })
        })
        .map(|p| p.with_file_name("out"))
        .filter(|o| o.exists())
        .context("Failed to find `out` directory for latest build")
}

fn generate_tar_gz(version: Version) -> Result<PathBuf> {
    let target = build_info::format!("{}", $.target.triple);
    let dist_pkg = DIST_DIR.join(format!("{PKG_NAME}-v{version}-{target}.tar.gz"));

    let binary = build_binary()?;
    ensure!(binary.exists(), "Failed to find package binary",);

    let _ = std::fs::remove_dir_all(&*DIST_DIR);
    std::fs::create_dir_all(&*DIST_DIR)?;

    let tar_gz = File::create(&dist_pkg)?;
    let enc = GzEncoder::new(tar_gz, Compression::default());
    let mut tar = Builder::new(enc);

    tar.append_path_with_name(binary, PathBuf::from("bin").join(PKG_NAME))?;
    tar.append_dir_all(".", out_dir()?)?;
    PKG_INCLUDE.iter().try_for_each(|p| tar.append_path(p))?;

    tar.into_inner()?.finish()?;

    Ok(dist_pkg)
}

fn build_binary() -> Result<PathBuf> {
    let status = Command::new("cargo")
        .arg("build")
        .arg("--release")
        .arg(format!("--package={PKG_NAME}"))
        .status()
        .context("Failed to invoke `cargo build`")?;

    anyhow::ensure!(status.success(), "Cargo returned an error");

    let mut binary = RELEASE_DIR.join(PKG_NAME);
    if cfg!(windows) {
        binary.set_extension("exe");
    };

    if let Err(e) = Command::new("strip").arg(&binary).status() {
        eprintln!("Failed to strip the binary: {}", e)
    }

    Ok(binary)
}

fn bump(prev: Version, level: Level, pre_release: Option<Prerelease>) -> Result<Version> {
    let mut next = prev.clone();

    match level {
        Level::Major => next.major += 1,
        Level::Minor => next.minor += 1,
        Level::Patch => next.patch += 1,
    };

    if let Some(pre) = pre_release {
        next.pre = pre;
    }

    bump_cargo(&next)?;
    bump_readme(&prev, &next)?;
    bump_changelog(&next)?;

    let cargo_update = Command::new("cargo")
        .arg("update")
        .arg("--workspace")
        .status()?;
    anyhow::ensure!(cargo_update.success(), "Failed to update cargo lockfile");

    let git_added = Command::new("git")
        .arg("add")
        .arg("./Cargo.lock")
        .status()?;
    anyhow::ensure!(git_added.success(), "Failed to add Cargo.lock to git");

    Ok(next)
}

fn bump_readme(prev: &Version, next: &Version) -> Result<()> {
    bump_file("./README.md", |contents| {
        Ok(contents.replace(&prev.to_string(), &next.to_string()))
    })
}

fn bump_changelog(next: &Version) -> Result<()> {
    bump_file("./CHANGELOG.md", |contents| {
        let date = chrono::Utc::now().format("%Y-%m-%d");

        let lines: Vec<String> = contents
            .lines()
            .flat_map(|line| {
                if line.starts_with("## [Unreleased]") {
                    vec![
                        line.to_owned(),
                        "".to_owned(),
                        format!("## [{next}] - {date}"),
                    ]
                } else if line.starts_with("[Unreleased]: ") {
                    vec![
                        line.to_owned(),
                        line.replace("[Unreleased]", &format!("[{next}]"))
                            .replace("HEAD", &format!("v{next}")),
                    ]
                } else {
                    vec![line.to_owned()]
                }
            })
            .collect();

        Ok(lines.join("\n"))
    })
}

fn bump_cargo(next: &Version) -> Result<()> {
    bump_file("./Cargo.toml", |contents| {
        let mut cargo_toml: toml_edit::Document = contents.parse()?;

        if cargo_toml["package"]["version"]["workspace"]
            .as_bool()
            .unwrap_or_default()
        {
            cargo_toml["workspace"]["package"]["version"] = toml_edit::value(next.to_string());
        } else if cargo_toml["package"]["version"].is_str() {
            cargo_toml["package"]["version"] = toml_edit::value(next.to_string());
        } else {
            anyhow::bail!("Failed to find version in Cargo.toml");
        };

        Ok(cargo_toml.to_string())
    })
}

fn bump_file<P, F>(path: P, mutator: F) -> Result<()>
where
    P: AsRef<Path>,
    F: Fn(String) -> Result<String>,
{
    let path = path.as_ref();

    let mut reader = BufReader::new(File::open(path)?);
    let mut buf = String::new();
    reader.read_to_string(&mut buf)?;

    let buf = mutator(buf)?;

    let mut writer = BufWriter::new(File::open(path)?);
    writer.write_all(buf.as_bytes())?;
    writer.flush()?;

    let git_added = Command::new("git").arg("add").arg(path).status()?;

    anyhow::ensure!(git_added.success(), "Failed to add bumped files to git");

    Ok(())
}

static PROJECT_ROOT: Lazy<PathBuf> = Lazy::new(|| {
    let dir = std::env::current_dir().unwrap_or_else(|_| {
        Path::new(env!("CARGO_MANIFEST_DIR"))
            .parent()
            .unwrap()
            .to_path_buf()
    });

    dir.ancestors()
        .find(|p| p.join(".git").is_dir())
        .unwrap_or(&dir)
        .to_path_buf()
});
static DIST_DIR: Lazy<PathBuf> = Lazy::new(|| PROJECT_ROOT.join("target").join("dist"));
static RELEASE_DIR: Lazy<PathBuf> = Lazy::new(|| PROJECT_ROOT.join("target").join("release"));

build_info::build_info!(fn build_info);