#![allow(unused_macros, dead_code)]

use std::{
    env,
    fmt,
    fs,
    path::PathBuf,
};

use clap::{Arg, Command, ValueEnum};

#[macro_use]
#[path = "src/print.rs"]
mod print;

#[macro_use]
#[path = "src/macros.rs"]
mod macros;

/// To appease the argparse module.
struct Config(());

mod argparse {
    include!("src/argparse/mod.rs");
}

#[path = "src/gpg_args.rs"]
mod gpg_args;

#[path = "src/gpgv_args.rs"]
mod gpgv_args;

fn main() {
    let mut gpg_sq = cli_gpg_sq();
    let mut gpgv_sq = cli_gpgv_sq();

    generate_shell_completions(&mut gpg_sq, &mut gpgv_sq).unwrap();
    generate_man_pages(gpg_sq, gpgv_sq).unwrap();
}

/// Variable name to control the asset out directory with.
const ASSET_OUT_DIR: &str = "ASSET_OUT_DIR";

/// Returns the directory to write the given assets to.
fn asset_out_dir(asset: &str) -> Result<PathBuf> {
    println!("cargo:rerun-if-env-changed={}", ASSET_OUT_DIR);
    let outdir: PathBuf =
        env::var_os(ASSET_OUT_DIR).unwrap_or_else(
            || env::var_os("OUT_DIR").expect("OUT_DIR not set")).into();
    if outdir.exists() && ! outdir.is_dir() {
        return Err(Error(
            format!("{}={:?} is not a directory", ASSET_OUT_DIR, outdir)).into());
    }

    let path = outdir.join(asset);
    fs::create_dir_all(&path)?;
    Ok(path)
}

/// Generates shell completions.
fn generate_shell_completions(gpg_sq: &mut clap::Command,
                              gpgv_sq: &mut clap::Command)
                              -> Result<()> {
    let path = asset_out_dir("shell-completions")?;

    for shell in clap_complete::Shell::value_variants() {
        clap_complete::generate_to(*shell, gpg_sq, "gpg-sq", &path)?;
        clap_complete::generate_to(*shell, gpgv_sq, "gpgv-sq", &path)?;
    };

    println!("cargo:warning=shell completions written to {}", path.display());
    Ok(())
}

/// Generates man pages.
fn generate_man_pages(gpg_sq: clap::Command,
                      gpgv_sq: clap::Command)
                      -> Result<()> {
    let path = asset_out_dir("man-pages")?;

    generate_man_page(gpg_sq, common_env(), gpg_files(),
                      fs::File::create(path.join("gpg-sq.1"))?)?;
    generate_man_page(gpgv_sq, common_env(), gpgv_files(),
                      fs::File::create(path.join("gpgv-sq.1"))?)?;

    println!("cargo:warning=man pages written to {}", path.display());

    Ok(())
}

type KeyValueIter = Box<dyn Iterator<Item = (&'static str, &'static str)>>;

/// Generates man pages.
fn generate_man_page(cmd: clap::Command,
                     env: KeyValueIter,
                     files: KeyValueIter,
                     mut sink: fs::File)
                     -> Result<()> {
    let has_authors = cmd.get_author().is_some();
    let man = clap_mangen::Man::new(cmd);

    man.render_title(&mut sink)?;
    man.render_name_section(&mut sink)?;
    man.render_synopsis_section(&mut sink)?;
    man.render_description_section(&mut sink)?;
    man.render_options_section(&mut sink)?;

    use roff::{Roff, bold, roman};
    let mut roff = Roff::default();

    roff.control("SH", ["ENVIRONMENT"]);
    for (key, value) in env {
        roff.control("TP", []);
        roff.text(vec![bold(key)]);
        roff.text(vec![roman(value)]);
    }

    roff.control("SH", ["FILES"]);
    for (key, value) in files {
        roff.control("TP", []);
        roff.text(vec![bold(key)]);
        roff.text(vec![roman(value)]);
    }

    roff.to_writer(&mut sink)?;

    man.render_version_section(&mut sink)?;

    if has_authors {
        man.render_authors_section(&mut sink)?;
    }

    Ok(())
}

fn common_env() -> KeyValueIter {
    Box::new([
        ("GNUPGHOME",
         "\
If set, must contain an absolute path to a directory containing the
GnuPG state, i.e. the configuration files, the cert rings, the secret
keys, and the trust database.  Can be overridden using the the option
`--gnupghome`.  If unset, and the option `--gnupghome` is not given,
defaults to `$HOME/.gnupg`.  In the FILES section below, `$GNUPGHOME`
is the location of the GnuPG state directory, independently on how it
is set (i.e. unset, set via `--gnupghome`, or set via `$GNUPGHOME).
"),

        ("SEQUOIA_CRYPTO_POLICY",
         "\
If set, must contain an absolute path to a configuration file that
changes which cryptographic algorithms are acceptable.  By default,
/etc/crypto-policies/back-ends/sequoia.config is read, which on Fedora
contains a reasonable policy set by the distribution.  See
https://docs.rs/sequoia-policy-config/latest/sequoia_policy_config/#format
for a description of the file format.
"),
    ].into_iter())
}

fn common_files() -> KeyValueIter {
    Box::new([
        ("/etc/crypto-policies/back-ends/sequoia.config",
         "\
Default cryptographic policy.  On Fedora, this contains a reasonable
policy set by the distribution.  Can be overridden using the
SEQUOIA_POLICY_CONFIG environment variable.  See
https://docs.rs/sequoia-policy-config/latest/sequoia_policy_config/#format
for a description of the file format.
")
    ].into_iter())
}

fn gpg_files() -> KeyValueIter {
    Box::new([
        // The various configuration files.
        ("$GNUPGHOME/gpg.conf",
         "\
GnuPG's main configuration file.
"),
        ("$GNUPGHOME/dirmngr.conf",
         "\
GnuPG's network configuration file.  gpg-sq reads this and honors a
subset of the options given.
"),

        // The various cert.d locations.
        ("$XDG_DATA_HOME/pgp.cert.d",
         "\
Default certificate store on POSIX systems if the default `GNUPGHOME`
is used.  This location is read and written to.
"),
        ("$HOME/Library/Application Support/pgp.cert.d",
         "\
Default certificate store on macOS if the default `GNUPGHOME` is used.
This location is read and written to.
"),
        ("{FOLDERID_RoamingAppData}/pgp.cert.d",
         "\
Default certificate store on Windows if the default `GNUPGHOME` is used.
This location is read and written to.
"),
        ("$GNUPGHOME/pubring.cert.d",
         "\
Certificate store if a non-default `GNUPGHOME` is used.  This location
is read and written to.
"),

        // The various pubrings.
        ("$GNUPGHOME/pubring.kbx",
         "\
GnuPG's default certificate store.  This file is read and monitored
for changes, but never changed.
"),
        ("$GNUPGHOME/pubring.gpg",
         "\
GnuPG's legacy certificate store.  This file is read and monitored
for changes, but never changed.
"),
        ("$GNUPGHOME/public-keys.d/pubring.db",
         "\
GnuPG 2.4.x's certificate store.  This file is read and monitored
for changes, but never changed.
"),

        // Secring.
        ("$GNUPGHOME/secring.gpg",
         "\
GnuPG's legacy secret key store.  gpg-sq does not use this file,
except for doing a migration from pre-2.1 state directories.
"),
        ("$GNUPGHOME/.gpg-v21-migrated",
         "\
Indicates that the state directory has been migrated from a pre-2.1
release.
"),

        // Trust database.
        ("$GNUPGHOME/trustdb.gpg",
         "\
GnuPG's trust database.  This file is read and monitored for changes,
but never modified.
"),

    ].into_iter().chain(common_files()))
}

fn gpgv_files() -> KeyValueIter {
    Box::new([
        ("$GNUPGHOME/trustedkeys.kbx",
         "\
The default set of trusted certificates.
"),
        ("$GNUPGHOME/trustedkeys.gpg",
         "\
Legacy default set of trusted certificates.  This file is read if
`trustedkeys.kbx` does not exist.
"),
    ].into_iter().chain(common_files()))
}

fn cli_gpg_sq() -> Command {
    let c = Command::new("gpg-sq")
        .version(env!("CARGO_PKG_VERSION"))
        .about("OpenPGP encryption and signing tool like gpg")
        .long_about(
            "This is a re-implementation and drop-in replacement of gpg using the Sequoia OpenPGP implementation.

gpg-sq is not feature-complete. It currently implements a commonly used subset of the signature creation and verification commands, the encryption and decryption commands, the key listing commands, and some miscellaneous commands.

Support for trust models is limited. Currently, the Web-of-Trust (\"pgp\") and always trust (\"always\") are implemented.",
        )
        .arg_required_else_help(true)
        .allow_external_subcommands(true)
        .arg(Arg::new("args")
             .value_name("ARGS")
             .required(false)
             .num_args(0..)
             .help("Additional arguments.  The semantics of the additional \
                    arguments, and if there are any, and how many, is \
                    dependent on the selected command."));


    add_options(gpg_args::OPTIONS, c)
}

fn cli_gpgv_sq() -> Command {
    let c = Command::new("gpgv-sq")
        .version(env!("CARGO_PKG_VERSION"))
        .about("gpgv-sq - Verify OpenPGP signatures like gpgv")
        .long_about(
            "This is a re-implementation and drop-in replacement of gpgv using the Sequoia OpenPGP implementation.

gpgv-sq is feature-complete. Please report any problems you encounter when replacing gpgv with gpgv-sq.",
        )
        .arg_required_else_help(true)
        .allow_external_subcommands(true)
        .arg(Arg::new("sig-file")
             .value_name("SIG-FILE")
             .required(false)
             .help("Signatures or inline-signed message to verify.  \
                    If not given, or `-` is given, the signature or \
                    inline-signed message is read from stdin."))
        .arg(Arg::new("dat-file")
             .value_name("DATA-FILE")
             .required(false)
             .num_args(1..)
             .help("If SIG-FILE is a detached signature, DATA-FILE \
                    is the data the signature is supposed to protect.  \
                    If given multiple times, the signature is assumed \
                    cover the concatenation of all files."));
    add_options(gpgv_args::OPTIONS, c)
}

fn add_options<T>(options: &[argparse::Opt<T>], mut c: Command)
                  -> Command
where
    T: Copy + fmt::Debug + Into<isize>
{
    use argparse::flags;
    use std::sync::Mutex;
    for commands in [true, false] {
        let section = Mutex::new(None);
        for o in options.iter()
            .filter(|o| if o.flags & flags::OPT_HEADER > 0 {
                *section.lock().unwrap() = Some(o.description.trim());
                false
            } else if o.flags == 0 && o.description.starts_with("@")
                    && o.description.len() > 1 {
                *section.lock().unwrap() = Some(&o.description[1..].trim());
                false
            } else {
                true
            })
            .filter(|o| o.description != "@")
            .filter(|o| (o.flags & flags::OPT_COMMAND > 0) == commands)
        {
            let (description, value_name) = if o.description.starts_with('|') {
                let d = &o.description[1..];
                let i = d.find('|').expect("matching | after value name");
                (&d[i + 1..], Some(&d[..i]))
            } else {
                (o.description, None)
            };

            let arg_name = if o.long_opt.is_empty() {
                Box::leak(
                    format!("{}", Into::<isize>::into(o.short_opt))
                        .into_boxed_str())
            } else {
                o.long_opt
            };
            let mut arg = Arg::new(arg_name)
                .help(description);

            if ! o.long_opt.is_empty() {
                arg = arg.long(o.long_opt);
            }

            if let Some(name) = value_name {
                arg = arg.value_name(name);
            }

            if let Some(s) = section.lock().unwrap().as_ref() {
                // XXX: This is not yet used, but might be in the future:
                // https://github.com/clap-rs/clap/issues/3363
                arg = arg.help_heading(s);
            }

            let short_opt: isize = o.short_opt.into();
            if short_opt < 256 {
                arg = arg.short(short_opt as u8 as char);
            }

            c = c.arg(arg);
        }
    }

    c
}

type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;

#[derive(Debug)]
struct Error(String);

impl fmt::Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}", self.0)
    }
}

impl std::error::Error for Error {}