use std::{
    env::set_current_dir,
    path::{Path, PathBuf},
    process::Command,
};

use clap::CommandFactory;
use colored::Colorize;
use glob::glob;

const MAIN_C: &str = include_str!("templates/main.c");
const GITIGNORE: &str = "target/\ncompile_commands.json\n";

#[derive(clap::Parser)]
#[clap(version, about)]
pub struct App {
    #[clap(subcommand)]
    command: Subcommand,
}

#[derive(clap::Subcommand)]
enum Subcommand {
    /// Create a new C project
    New {
        /// The name of the new project
        name: String,
    },
    /// Initialize a new C project
    Init,
    /// Run the local project
    Run {
        /// Force recompilation of the project
        #[arg(long, short)]
        force_recompile: bool,
        /// The build mode to use
        mode: Option<String>,
        /// Arguments to pass to the project binary
        #[arg(long, short)]
        args: Option<Vec<String>>,
    },
    /// Build the local project
    Build {
        /// Force recompilation of the project
        #[arg(long, short)]
        force_recompile: bool,
        /// The build mode to use
        mode: Option<String>,
    },
    /// Clean all in progress files
    Clean,
    /// Utility functions
    Utils {
        #[clap(subcommand)]
        command: UtilSubcommand,
    },
    /// List available build modes
    List,
    /// Add a new package to the project (throguh pkg-config)
    Add {
        /// The package to be added
        package: String,
    },
}

#[derive(clap::Subcommand)]
enum UtilSubcommand {
    /// Generate shell completions
    Completions {
        /// The shell to generate completions for
        #[arg(value_enum, long, short)]
        shell: ShellCompletions,
    },
    /// Generate compile_commands.json for IDE support
    GenCompileCommands {
        /// The build mode to generate for
        mode: Option<String>,
    },
}

#[derive(Clone, clap::ValueEnum)]
enum ShellCompletions {
    Bash,
    Fish,
    PowerShell,
    Zsh,
}

impl App {
    pub fn run(self) {
        match self.command {
            Subcommand::New { name } => {
                if let Err(e) = create_project(&name) {
                    eprintln!("Error creating project '{name}': {e}");
                    std::process::exit(1);
                }
            }
            Subcommand::Init => {
                if let Err(e) = create_project(".") {
                    eprintln!("Error initializing project: {e}");
                    std::process::exit(1);
                }
            }
            Subcommand::Run {
                mode,
                args,
                force_recompile,
            } => {
                if let Err(e) = build(&mode, force_recompile) {
                    eprintln!("Error building project: {e}");
                    std::process::exit(1);
                };
                if let Err(e) = run(&mode, args) {
                    eprintln!("Error running project: {e}");
                    std::process::exit(1);
                }
            }
            Subcommand::Build {
                mode,
                force_recompile,
            } => {
                if let Err(e) = build(&mode, force_recompile) {
                    eprintln!("Error building project: {e}");
                    std::process::exit(1);
                }
            }
            Subcommand::Clean => {
                if let Err(e) = clean() {
                    eprintln!("Error cleaning project: {e}");
                    std::process::exit(1);
                }
            }
            Subcommand::Utils { command } => match command {
                UtilSubcommand::Completions { shell } => {
                    let name = env!("CARGO_PKG_NAME");
                    let mut command = App::command();
                    match shell {
                        ShellCompletions::Bash => clap_complete::generate(
                            clap_complete::shells::Bash,
                            &mut command,
                            name,
                            &mut std::io::stdout(),
                        ),
                        ShellCompletions::Fish => clap_complete::generate(
                            clap_complete::shells::Fish,
                            &mut command,
                            name,
                            &mut std::io::stdout(),
                        ),
                        ShellCompletions::PowerShell => clap_complete::generate(
                            clap_complete::shells::PowerShell,
                            &mut command,
                            name,
                            &mut std::io::stdout(),
                        ),
                        ShellCompletions::Zsh => clap_complete::generate(
                            clap_complete::shells::Zsh,
                            &mut command,
                            name,
                            &mut std::io::stdout(),
                        ),
                    }
                }
                UtilSubcommand::GenCompileCommands { mode } => {
                    if let Err(e) = gen_compile_commands(&mode) {
                        eprintln!("Error generating compile commands: {e}");
                        std::process::exit(1);
                    }
                }
            },
            Subcommand::List => {
                if let Err(e) = list() {
                    eprintln!("Error listing build profiles: {e}");
                    std::process::exit(1);
                }
            }
            Subcommand::Add { package } => {
                if let Err(e) = add_package(&package) {
                    eprintln!("Error adding package {package} to project: {e}");
                    std::process::exit(1);
                }
            }
        }
    }
}

fn add_package(package: &str) -> std::io::Result<()> {
    let status = Command::new("pkg-config")
        .arg("--exists")
        .arg(&package)
        .status()
        .map_err(|_| {
            std::io::Error::new(
                std::io::ErrorKind::NotFound,
                "pkg-config not found - please install it first",
            )
        })?;

    if !status.success() {
        eprintln!(
            "  {} pkg-config could not find package '{package}'",
            "Error".red().bold()
        );
        eprintln!(
            "  {} try installing the development package for '{package}', e.g.:",
            "Hint".yellow().bold()
        );
        eprintln!("       Arch:   sudo pacman -S {package}");
        eprintln!("       Debian: sudo apt install lib{package}-dev");
        std::process::exit(1);
    }

    let mut conf = get_config().ok_or(std::io::Error::new(
        std::io::ErrorKind::NotFound,
        "no Pallet.toml found in local directory",
    ))?;

    let deps = conf.dependencies.get_or_insert_with(Vec::new);

    if deps.contains(&package.to_owned()) {
        println!(
            "  {} '{package}' is already a dependency",
            "Warning".yellow().bold()
        );
        return Ok(());
    }

    deps.push(package.to_owned());

    std::fs::write(
        "Pallet.toml",
        toml::to_string_pretty(&conf).expect("valid TOML"),
    )?;

    println!("  {} {package}", "Added".green().bold());

    Ok(())
}

fn gen_compile_commands(mode: &Option<String>) -> std::io::Result<()> {
    let conf = get_config().ok_or(std::io::Error::new(
        std::io::ErrorKind::NotFound,
        "no Pallet.toml found in current directory",
    ))?;

    let build_config = conf.get_or_default(mode).ok_or(std::io::Error::new(
        std::io::ErrorKind::NotFound,
        "build layout not found",
    ))?;

    let compiler = conf.compiler.as_deref().unwrap_or("gcc");
    let cwd = std::env::current_dir()?;
    let obj_dir = format!("target/{}/obj", build_config.name);

    let source_files: Vec<PathBuf> = glob("src/*.c")
        .map_err(|e| std::io::Error::new(std::io::ErrorKind::NotFound, format!("{e}")))?
        .filter_map(|e| e.ok())
        .collect();

    let entries: Vec<serde_json::Value> = source_files
        .iter()
        .map(|src| {
            let stem = src.file_stem().unwrap().to_string_lossy();
            let obj = format!("{}/{}.o", obj_dir, stem);
            let command = std::iter::once(compiler.to_string())
                .chain(build_config.args.iter().cloned())
                .chain(["-c".to_string(), src.to_string_lossy().to_string()])
                .chain(["-o".to_string(), obj])
                .collect::<Vec<_>>()
                .join(" ");
            serde_json::json!({
                "directory": cwd.to_string_lossy(),
                "file": cwd.join(src).to_string_lossy(),
                "command": command
            })
        })
        .collect();

    let json = serde_json::to_string_pretty(&entries)
        .map_err(|e| std::io::Error::new(std::io::ErrorKind::Other, format!("{e}")))?;

    std::fs::write("compile_commands.json", json)?;

    println!("  {} compile_commands.json", "Generated".green().bold());

    Ok(())
}

fn list() -> std::io::Result<()> {
    let conf = get_config().ok_or(std::io::Error::new(
        std::io::ErrorKind::NotFound,
        "no Pallet.toml found in local directory",
    ))?;
    for build in conf.build {
        println!(" - {}: {:?}", build.name.green().bold(), build.args);
    }

    Ok(())
}

fn create_project<P: AsRef<Path>>(directory: P) -> std::io::Result<()> {
    let name = if directory.as_ref().to_string_lossy() == "." {
        String::new()
    } else {
        format!(" '{}'", directory.as_ref().to_string_lossy())
    };

    println!(
        "  {} binary (application){}",
        "Creating".green().bold(),
        name
    );

    let pathdir = directory.as_ref();

    if pathdir.exists() && pathdir.to_string_lossy() != "." {
        return Err(std::io::Error::new(
            std::io::ErrorKind::AlreadyExists,
            "specified directory already exists",
        ));
    }

    if !pathdir.exists() && pathdir.to_string_lossy() != "." {
        std::fs::create_dir(pathdir)?;
    }

    set_current_dir(pathdir)?;

    std::fs::create_dir("src")?;

    std::fs::write("src/main.c", MAIN_C)?;
    std::fs::write(".gitignore", GITIGNORE)?;

    let config = crate::config::Config::new(&pathdir.to_string_lossy());

    let serial = toml::to_string_pretty(&config).expect("a valid TOML structure");

    std::fs::write("Pallet.toml", &serial)?;

    Ok(())
}

fn get_config() -> Option<crate::config::Config> {
    let p = PathBuf::from("Pallet.toml");
    if !p.exists() {
        return None;
    }
    let raw = std::fs::read_to_string(&p).expect("A valid config file");

    toml::from_str(&raw).ok()
}

fn build(mode: &Option<String>, force_recompile: bool) -> std::io::Result<()> {
    let conf = match get_config() {
        Some(conf) => conf,
        None => {
            eprintln!("Error opening config file. No Pallet.toml in current directory.");
            std::process::exit(1);
        }
    };

    let build_config = conf.get_or_default(mode).ok_or(std::io::Error::new(
        std::io::ErrorKind::NotFound,
        "build layout not found",
    ))?;

    println!(
        "  {} '{}' profile for project '{}'",
        "Building".green().bold(),
        build_config.name,
        conf.name
    );

    let start = std::time::Instant::now();

    let obj_dir = format!("target/{}/obj", build_config.name);

    std::fs::create_dir_all(&obj_dir)?;

    let compiler = conf.compiler.as_deref().unwrap_or("gcc");

    let mut extra_compile_flags: Vec<String> = Vec::new();
    let mut extra_link_flags: Vec<String> = Vec::new();

    if let Some(deps) = &conf.dependencies {
        if !deps.is_empty() {
            let cflags = Command::new("pkg-config")
                .arg("--cflags")
                .args(deps)
                .output()
                .map_err(|_| {
                    std::io::Error::new(std::io::ErrorKind::NotFound, "pkg-config not found")
                })?;
            if !cflags.status.success() {
                return Err(std::io::Error::new(
                    std::io::ErrorKind::Other,
                    "pkg-config --cflags failed - is the package installed?",
                ));
            }

            let libs = Command::new("pkg-config")
                .arg("--libs")
                .args(deps)
                .output()
                .map_err(|_| {
                    std::io::Error::new(std::io::ErrorKind::NotFound, "pkg-config not found")
                })?;
            if !libs.status.success() {
                return Err(std::io::Error::new(
                    std::io::ErrorKind::Other,
                    "pkg-config --libs failed - is the pacakge installed?",
                ));
            }

            extra_compile_flags = String::from_utf8_lossy(&cflags.stdout)
                .split_whitespace()
                .map(str::to_owned)
                .collect();
            extra_link_flags = String::from_utf8_lossy(&libs.stdout)
                .split_whitespace()
                .map(str::to_owned)
                .collect();
        }
    }

    let source_files: Vec<PathBuf> = glob("src/*.c")
        .map_err(|e| std::io::Error::new(std::io::ErrorKind::NotFound, format!("{e}")))?
        .filter_map(|e| e.ok())
        .collect();

    let mut any_changed = false;

    for src in &source_files {
        let stem = src.file_stem().unwrap().to_string_lossy();
        let obj_path = format!("{}/{}.o", obj_dir, stem);
        let hash_path = format!("{}/{}.c.hash", obj_dir, stem);

        let hash = hash_file(src)?;

        let needs_compile = force_recompile
            || match std::fs::read_to_string(&hash_path) {
                Ok(old) => old.trim() != hash.trim(),
                Err(_) => true,
            };

        if needs_compile {
            println!(" {} {}", "Compiling".green().bold(), src.display());

            let status = Command::new(compiler)
                .args(&build_config.args)
                .args(&extra_compile_flags)
                .arg("-c")
                .arg(src)
                .arg("-o")
                .arg(&obj_path)
                .status()?;

            if !status.success() {
                return Err(std::io::Error::new(
                    std::io::ErrorKind::Other,
                    format!("failed to compile {}", src.display()),
                ));
            }

            std::fs::write(&hash_path, &hash)?;
            any_changed = true;
        }
    }

    let binary = format!("target/{}/{}", build_config.name, conf.name);
    let binary_exists = PathBuf::from(&binary).exists();

    if !any_changed && binary_exists {
        println!(
            "   {} (code not changed, recompile not made)",
            "Finished".green().bold()
        );
        return Ok(());
    }

    let obj_files: Vec<String> = source_files
        .iter()
        .map(|src| {
            let stem = src.file_stem().unwrap().to_string_lossy();
            format!("{}/{}.o", obj_dir, stem)
        })
        .collect();

    let status = Command::new(compiler)
        .args(&obj_files)
        .args(&extra_link_flags)
        .arg("-o")
        .arg(&binary)
        .status()?;

    if !status.success() {
        return Err(std::io::Error::new(
            std::io::ErrorKind::Other,
            "linking failed",
        ));
    }

    let stop = start.elapsed();

    gen_compile_commands(&mode)?;

    println!(
        "   {} '{}' profile for project '{}' in {:.2}s",
        "Finished".green().bold(),
        build_config.name,
        conf.name,
        stop.as_secs_f64()
    );

    Ok(())
}

fn hash_file(path: &Path) -> std::io::Result<String> {
    let contents = std::fs::read_to_string(path)?;
    Ok(sha256::digest(contents))
}

fn run(mode: &Option<String>, args: Option<Vec<String>>) -> std::io::Result<()> {
    let conf = match get_config() {
        Some(conf) => conf,
        None => {
            eprintln!("Error opening config file. No Pallet.toml in current directory.");
            std::process::exit(1);
        }
    };

    let build_config = conf.get_or_default(mode).ok_or(std::io::Error::new(
        std::io::ErrorKind::NotFound,
        "build layout not found",
    ))?;

    println!(
        "    {} '{}' profile for project '{}'",
        "Running".green().bold(),
        build_config.name,
        conf.name
    );

    let mut command = Command::new(format!("target/{}/{}", build_config.name, conf.name));

    if let Some(args) = args {
        for arg in args {
            command.arg(arg);
        }
    }

    let mut child = command.spawn()?;

    child.wait()?;

    Ok(())
}

fn clean() -> std::io::Result<()> {
    if get_config().is_none() {
        return Err(std::io::Error::new(
            std::io::ErrorKind::NotFound,
            "no Pallet.toml found in local dir",
        ));
    }

    std::fs::remove_dir_all("target/")?;

    println!(
        "  {} removed files in target/ directory",
        "Successfully".green().bold()
    );

    Ok(())
}