use {
    derive_more::Display,
    error_stack::{bail, report, Context, Report, Result, ResultExt},
    fatfs::{FileSystem, FormatVolumeOptions, FsOptions, ReadWriteSeek},
    std::{
        fmt::Display,
        fs::{self, File},
        io::{self, Write},
        path::Path,
        process::{exit, Command},
    },
};

fn main() -> Result<(), Error> {
    let mut args = std::env::args();
    args.next();

    // let disk_meta = fs::metadata("target/disk.img").unwrap();
    // let config_meta = fs::metadata("system.toml").unwrap();

    // if disk_meta.modified().unwrap() < config_meta.modified().unwrap() {
    //     // TODO: work on adding in system.toml support
    //     // TODO: rebuild the disk
    // }

    match args.next().as_deref() {
        Some("build" | "b") => {
            let mut release = false;
            let mut target = Target::X86_64;
            for arg in args {
                if arg == "-r" || arg == "--release" {
                    release = true;
                } else if arg == "rv64" || arg == "riscv64" || arg == "riscv64-virt" {
                    target = Target::Riscv64Virt;
                } else if arg == "arm64" || arg == "aarch64" || arg == "aarch64-virt" {
                    target = Target::Aarch64;
                } else {
                    return Err(report!(Error::InvalidSubCom));
                }
            }

            assemble()?;
            build(release, target).change_context(Error::Build)
        }
        Some("run" | "r") => {
            let mut release = false;
            let mut target = Target::X86_64;
            for arg in args {
                if arg == "-r" || arg == "--release" {
                    release = true;
                } else if arg == "rv64" || arg == "riscv64" || arg == "riscv64-virt" {
                    target = Target::Riscv64Virt;
                } else if arg == "arm64" || arg == "aarch64" || arg == "aarch64-virt" {
                    target = Target::Aarch64;
                } else {
                    return Err(report!(Error::InvalidSubCom));
                }
            }

            assemble()?;
            build(release, target)?;
            run(release, target)
        }
        Some("help" | "h") => {
            println!(concat!(
                "AbleOS RepBuild\n",
                "Subcommands:\n",
                "  build (b): Build a bootable disk image\n",
                "   help (h): Print this message\n",
                "    run (r): Build and run AbleOS in QEMU\n\n",
                "Options for build and run:\n",
                "        -r: build in release mode",
                "  [target]: sets target"
            ),);
            Ok(())
        }
        _ => Err(report!(Error::InvalidSubCom)),
    }
}

fn assemble() -> Result<(), Error> {
    match std::fs::create_dir("target/test-programs") {
        Ok(_) => (),
        Err(e) if e.kind() == std::io::ErrorKind::AlreadyExists => (),
        Err(e) => return Err(Report::new(e).change_context(Error::Io)),
    }

    for entry in std::fs::read_dir("sysdata/test-programs")
        .map_err(Report::from)
        .change_context(Error::Io)?
    {
        let entry = entry.map_err(Report::from).change_context(Error::Io)?;
        if !entry
            .file_type()
            .map_err(Report::from)
            .change_context(Error::Io)?
            .is_file()
        {
            continue;
        }

        let name = entry.file_name();
        let name = name.to_string_lossy();
        let name = name.trim_end_matches(".rhai");

        let mut out = File::options()
            .write(true)
            .create(true)
            .open(Path::new("target/test-programs").join(format!("{name}.hbf")))
            .map_err(Report::from)
            .change_context(Error::Io)?;

        out.set_len(0)
            .map_err(Report::from)
            .change_context(Error::Io)?;

        hbasm::assembler(&mut out, |engine| engine.run_file(entry.path()))
            .map_err(|e| report!(Error::Assembler).attach_printable(e.to_string()))?;
    }

    Ok(())
}

fn get_fs() -> Result<FileSystem<impl ReadWriteSeek>, io::Error> {
    let filename = "sysdata/system_config.toml";

    let mut img = File::options()
        .read(true)
        .write(true)
        .create(true)
        .open(Path::new("target/disk.img"))?;

    img.set_len(1024 * 1024 * 64)?;

    fatfs::format_volume(&mut img, FormatVolumeOptions::new())?;

    let fs = FileSystem::new(img, FsOptions::new())?;

    // Read the contents of the file using a `match` block
    // to return the `data: Ok(c)` as a `String`
    // or handle any `errors: Err(_)`.
    let contents = match fs::read_to_string(filename) {
        // If successful return the files text as `contents`.
        // `c` is a local variable.
        Ok(c) => c,
        // Handle the `error` case.
        Err(_) => {
            // Write `msg` to `stderr`.
            eprintln!("Could not read file `{}`", filename);
            // Exit the program with exit code `1`.
            exit(1);
        }
    };
    use toml::Value;

    let mut limine_str = String::new();

    let mut data: Value = toml::from_str(&contents).unwrap();
    let boot_table = data.get_mut("boot");
    let limine_table = boot_table.unwrap().get_mut("limine").unwrap();
    let default_entry = limine_table.get("default_entry").unwrap();
    let timeout = limine_table.get("timeout").unwrap();
    let interface_resolution = limine_table.get("interface_resolution").unwrap();
    let verbose = limine_table.get("verbose").unwrap();
    let term_wallpaper = limine_table.get("term_wallpaper").unwrap();

    let vb_post = match verbose.as_bool().unwrap() {
        true => "yes",
        false => "no",
    };
    let term_background = limine_table
        .get("term_backdrop")
        .unwrap_or(&Value::Integer(0));
    let base = format!(
        "DEFAULT_ENTRY={}
TIMEOUT={}
VERBOSE={}
INTERFACE_RESOLUTION={}
# Terminal related settings
TERM_WALLPAPER={}
TERM_BACKDROP={}
",
        default_entry,
        timeout,
        vb_post,
        interface_resolution,
        term_wallpaper.as_str().unwrap(),
        term_background
    );

    // Copy the term_wallpaper to the image
    let term_wallpaper_path = term_wallpaper
        .as_str()
        .unwrap()
        .split("boot:///")
        .last()
        .unwrap();
    copy_file_to_img(&format!("sysdata/{}", term_wallpaper_path), &fs);

    limine_str.push_str(&base);

    let boot_entries = limine_table.as_table_mut().unwrap();
    let mut real_boot_entries = boot_entries.clone();
    for (key, value) in boot_entries.into_iter() {
        if !value.is_table() {
            real_boot_entries.remove(key);
        }
    }

    for (name, mut value) in real_boot_entries {
        let comment = value.get("comment").unwrap();
        let protocol = value.get("protocol").unwrap();
        let resolution = value.get("resolution").unwrap();
        let kernel_path = value.get("kernel_path").unwrap();
        let kernel_cmdline = value.get("kernel_cmdline").unwrap();

        let text_entry = format!(
            "
:{}
    COMMENT={}
    PROTOCOL={}
    RESOLUTION={}
    KERNEL_PATH={}
    KERNEL_CMDLINE={}

",
            name,
            comment.as_str().unwrap(),
            protocol.as_str().unwrap(),
            resolution.as_str().unwrap(),
            kernel_path.as_str().unwrap(),
            kernel_cmdline,
        );

        limine_str.push_str(&text_entry);

        let modules = value.get_mut("modules").unwrap().as_table_mut().unwrap();
        // let mut real_modules = modules.clone();

        for (key, value) in modules.into_iter() {
            if value.is_table() {
                let path = value.get("path").expect("You must have `path` as a value");
                let default_value = Value::String("".into());
                let cmd_line = value.get("cmd_line").unwrap_or(&default_value);

                let a = format!(
                    "    MODULE_PATH={}
    MODULE_CMDLINE={}\n\n",
                    path.as_str().unwrap(),
                    cmd_line
                );
                limine_str.push_str(&a);
            }
        }

        // Copy modules into the test_programs directory
        modules.into_iter().for_each(|(key, value)| {
            if value.is_table() {
                let path = value
                    .get("path")
                    .expect("You must have a `path` as a value")
                    .as_str()
                    .unwrap()
                    .split("boot:///")
                    .last()
                    .unwrap();
                let fpath = format!("target/test-programs/{}", path);
                copy_file_to_img(&fpath, &fs);
            }
        });
    }

    let bootdir = fs.root_dir().create_dir("efi")?.create_dir("boot")?;

    let mut f = fs.root_dir().create_file("limine.cfg")?;
    let a = f.write(limine_str.as_bytes())?;
    drop(f);

    io::copy(
        &mut File::open("limine/BOOTX64.EFI")
            .map_err(Report::from)
            .attach_printable("Copying Limine (x86_64): have you pulled the submodule?")?,
        &mut bootdir.create_file("bootx64.efi")?,
    )?;

    io::copy(
        &mut File::open("limine/BOOTAA64.EFI")
            .map_err(Report::from)
            .attach_printable("Copying Limine (ARM): have you pulled the submodule?")?,
        &mut bootdir.create_file("bootaa64.efi")?,
    )?;

    drop(bootdir);
    Ok(fs)
}

fn copy_file_to_img(fpath: &str, fs: &FileSystem<File>) {
    let path = Path::new(fpath);
    io::copy(
        &mut File::open(path).expect(&format!("Could not open file {fpath}")),
        &mut fs
            .root_dir()
            .create_file(&path.file_name().unwrap().to_string_lossy())
            .expect("Unable to create file"),
    )
    .expect("Copy failed");
}

fn build(release: bool, target: Target) -> Result<(), Error> {
    let fs = get_fs().change_context(Error::Io)?;
    let mut com = Command::new("cargo");
    com.current_dir("kernel");
    com.args(["b"]);
    if release {
        com.arg("-r");
    }

    if target == Target::Riscv64Virt {
        com.args(["--target", "targets/riscv64-virt-ableos.json"]);
    }
    if target == Target::Aarch64 {
        com.args(["--target", "targets/aarch64-virt-ableos.json"]);
    }

    match com.status() {
        Ok(s) if s.code() != Some(0) => bail!(Error::Build),
        Err(e) => bail!(report!(e).change_context(Error::Build)),
        _ => (),
    }

    let mut path: String = "kernel".to_string();
    let kernel_dir = match target {
        Target::X86_64 => {
            path.push_str("_x86-64");
            "target/x86_64-ableos"
        }
        Target::Riscv64Virt => "target/riscv64-virt-ableos",
        Target::Aarch64 => {
            path.push_str("_aarch64");
            "target/aarch64-virt-ableos"
        }
    };

    (|| -> std::io::Result<_> {
        io::copy(
            &mut File::open(
                Path::new(kernel_dir)
                    .join(if release { "release" } else { "debug" })
                    .join("kernel"),
            )?,
            &mut fs.root_dir().create_file(&path)?,
        )
        .map(|_| ())
    })()
    .map_err(Report::from)
    .change_context(Error::Io)
}

fn run(release: bool, target: Target) -> Result<(), Error> {
    let mut com = match target {
        Target::X86_64 => Command::new("qemu-system-x86_64"),
        Target::Riscv64Virt => Command::new("qemu-system-riscv64"),
        Target::Aarch64 => Command::new("qemu-system-aarch64"),
    };
    let ovmf_path = fetch_ovmf(target);

    match target {
        Target::X86_64 => {
            #[rustfmt::skip]
            com.args([
                "-bios", &ovmf_path.change_context(Error::OvmfFetch)?,
                "-drive", "file=target/disk.img,format=raw",
                "-m", "4G",
                "-smp", "cores=4",
                // "-enable-kvm",
                "-cpu", "Broadwell-v4"
            ]);
        }
        Target::Riscv64Virt => {
            #[rustfmt::skip]
            com.args([
                "-M", "virt",
                "-m", "128M",
                "-serial", "stdio",
                "-kernel",
                if release {
                    "target/riscv64-virt-ableos/release/kernel"
                } else {
                    "target/riscv64-virt-ableos/debug/kernel"
                }
            ]);
        }
        Target::Aarch64 => {
            #[rustfmt::skip]
            com.args([
                "-M", "virt",
                "-cpu", "cortex-a72",
                "-device", "ramfb",
                "-device", "qemu-xhci",
                "-device", "usb-kbd",
                "-m", "2G",
                "-bios", &ovmf_path.change_context(Error::OvmfFetch)?,
                "-drive", "file=target/disk.img,format=raw",
            ]);
        }
    }

    match com
        .status()
        .map_err(Report::from)
        .change_context(Error::ProcessSpawn)?
    {
        s if s.success() => Ok(()),
        s => Err(report!(Error::Qemu(s.code()))),
    }
}

fn fetch_ovmf(target: Target) -> Result<String, OvmfFetchError> {
    let (ovmf_url, ovmf_path) = match target {
        Target::X86_64 => (
            "https://retrage.github.io/edk2-nightly/bin/RELEASEX64_OVMF.fd",
            "target/RELEASEX64_OVMF.fd",
        ),
        Target::Riscv64Virt => return Err(OvmfFetchError::Empty.into()),
        Target::Aarch64 => (
            "https://retrage.github.io/edk2-nightly/bin/RELEASEAARCH64_QEMU_EFI.fd",
            "target/RELEASEAARCH64_QEMU_EFI.fd",
        ),
    };

    let mut file = match std::fs::metadata(ovmf_path) {
        Err(e) if e.kind() == std::io::ErrorKind::NotFound => std::fs::OpenOptions::new()
            .create(true)
            .write(true)
            .read(true)
            .open(ovmf_path)
            .map_err(Report::from)
            .change_context(OvmfFetchError::Io)?,
        Ok(_) => return Ok(ovmf_path.to_owned()),
        Err(e) => return Err(report!(e).change_context(OvmfFetchError::Io)),
    };
    let mut bytes = reqwest::blocking::get(ovmf_url)
        .map_err(Report::from)
        .change_context(OvmfFetchError::Fetch)?;

    bytes
        .copy_to(&mut file)
        .map_err(Report::from)
        .change_context(OvmfFetchError::Io)?;

    Ok(ovmf_path.to_owned())
}

#[derive(Debug, Display)]
enum OvmfFetchError {
    #[display(fmt = "Failed to fetch OVMF package")]
    Fetch,
    #[display(fmt = "No OVMF package available")]
    Empty,
    #[display(fmt = "IO Error")]
    Io,
}

impl Context for OvmfFetchError {}

#[derive(Clone, Copy, PartialEq, Eq)]
enum Target {
    X86_64,
    Riscv64Virt,
    Aarch64,
}

#[derive(Debug, Display)]
enum Error {
    #[display(fmt = "Failed to build the kernel")]
    Build,
    #[display(fmt = "Missing or invalid subcommand (available: build, run)")]
    InvalidSubCom,
    #[display(fmt = "IO Error")]
    Io,
    #[display(fmt = "Failed to spawn a process")]
    ProcessSpawn,
    #[display(fmt = "Failed to fetch UEFI firmware")]
    OvmfFetch,
    #[display(fmt = "Failed to assemble Holey Bytes code")]
    Assembler,
    #[display(fmt = "QEMU Error: {}", "fmt_qemu_err(*_0)")]
    Qemu(Option<i32>),
}

impl Context for Error {}

fn fmt_qemu_err(e: Option<i32>) -> impl Display {
    struct W(Option<i32>);
    impl Display for W {
        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
            if let Some(c) = self.0 {
                c.fmt(f)
            } else {
                f.write_str("Interrupted by signal")
            }
        }
    }

    W(e)
}