use core::str;

use std::{collections::hash_map::Entry, ffi::OsString};

use format_bytes::format_bytes;

use hg::{

    encoding::Encoder,

    operations::{

        annotate, AnnotateOptions, AnnotateOutput, ChangesetAnnotation,

    },

    revlog::changelog::Changelog,

    FastHashMap, Revision,

};

use crate::{error::CommandError, utils::path_utils::resolve_file_args};

pub const HELP_TEXT: &str = "

show changeset information by line for each file

";

pub fn args() -> clap::Command {

    clap::command!("annotate")

        .alias("blame")

        .arg(

            clap::Arg::new("files")

                .help("files to annotate")

                .required(true)

                .num_args(1..)

                .value_name("FILE")

                .value_parser(clap::value_parser!(OsString)),

        )

        .arg(

            clap::Arg::new("rev")

                .help("annotate the specified revision")

                .short('r')

                .long("rev")

                .value_name("REV")

                .default_value("."),

        )

        .arg(

            clap::Arg::new("no-follow")

                .help("don't follow copies and renames")

                .long("no-follow")

                .action(clap::ArgAction::SetTrue),

        )

        .arg(

            clap::Arg::new("text")

                .help("treat all files as text")

                .short('a')

                .long("text")

                .action(clap::ArgAction::SetTrue),

        )

        .arg(

            clap::Arg::new("user")

                .help("list the author (long with -v)")

                .short('u')

                .long("user")

                .action(clap::ArgAction::SetTrue),

        )

        .arg(

            clap::Arg::new("number")

                .help("list the revision number (default)")

                .short('n')

                .long("number")

                .action(clap::ArgAction::SetTrue),

        )

        .arg(

            clap::Arg::new("changeset")

                .help("list the changeset")

                .short('c')

                .long("changeset")

                .action(clap::ArgAction::SetTrue),

        )

        .arg(

            clap::Arg::new("date")

                .help("list the date (short with -q)")

                .short('d')

                .long("date")

                .action(clap::ArgAction::SetTrue),

        )

        .arg(

            clap::Arg::new("file")

                .help("list the filename")

                .short('f')

                .long("file")

                .action(clap::ArgAction::SetTrue),

        )

        .arg(

            clap::Arg::new("line-number")

                .help("show the line number at the first appearance")

                .short('l')

                .long("line-number")

                .action(clap::ArgAction::SetTrue),

        )

        .arg(

            clap::Arg::new("quiet")

                .help("show short date for -d")

                .short('q')

                .long("quiet")

                .action(clap::ArgAction::SetTrue),

        )

        .arg(

            clap::Arg::new("verbose")

                .help("show full username for -u")

                .short('v')

                .long("verbose")

                .action(clap::ArgAction::SetTrue)

                .conflicts_with("quiet"),

        )

        .about(HELP_TEXT)

}

pub fn run(invocation: &crate::CliInvocation) -> Result<(), CommandError> {

    let config = invocation.config;

    if config.has_non_empty_section(b"annotate") {

        return Err(CommandError::unsupported(

            "rhg annotate does not support any [annotate] configs",

        ));

    }

    let repo = invocation.repo?;

    let args = invocation.subcommand_args;

    let rev = args.get_one::<String>("rev").expect("rev has a default");

    let rev = hg::revset::resolve_single(rev, repo)?;

    let files = match args.get_many::<OsString>("files") {

        None => vec![],

        Some(files) => resolve_file_args(repo, files)?,

    };

    let options = AnnotateOptions {

        treat_binary_as_text: args.get_flag("text"),

        follow_copies: !args.get_flag("no-follow"),

    };

    let mut include = Include {

        user: args.get_flag("user"),

        number: args.get_flag("number"),

        changeset: args.get_flag("changeset"),

        date: args.get_flag("date"),

        file: args.get_flag("file"),

        line_number: args.get_flag("line-number"),

    };

    if !(include.user || include.file || include.date || include.changeset) {

        include.number = true;

    }

    if include.line_number && !(include.number || include.changeset) {

        return Err(CommandError::abort(

            "at least one of -n/-c is required for -l",

        ));

    }

    let verbosity = match (args.get_flag("quiet"), args.get_flag("verbose")) {

        (false, false) => Verbosity::Default,

        (true, false) => Verbosity::Quiet,

        (false, true) => Verbosity::Verbose,

        (true, true) => unreachable!(),

    };

    let changelog = repo.changelog()?;

    let mut formatter = Formatter::new(

        &changelog,

        invocation.ui.encoder(),

        include,

        verbosity,

    );

    let mut stdout = invocation.ui.stdout_buffer();

    for path in files {

        match annotate(repo, &path, rev, options)? {

            AnnotateOutput::Text(text) => {

                let annotations = formatter.format(text.annotations)?;

                for (annotation, line) in annotations.iter().zip(&text.lines) {

                    stdout.write_all(&format_bytes!(

                        b"{}: {}", annotation, line

                    ))?;

                }

                if let Some(line) = text.lines.last() {

                    if !line.ends_with(b"\n") {

                        stdout.write_all(b"\n")?;

                    }

                }

            }

            AnnotateOutput::Binary => {

                stdout.write_all(&format_bytes!(

                    b"{}: binary file\n",

                    path.as_bytes()

                ))?;

            }

            AnnotateOutput::NotFound => {

                let short = changelog.node_from_rev(rev).short();

                return Err(CommandError::abort(format!(

                    "{path}: no such file in rev {short:x}",

                )));

            }

        }

    }

    stdout.flush()?;

    Ok(())

}

struct Formatter<'a> {

    changelog: &'a Changelog,

    encoder: &'a Encoder,

    include: Include,

    verbosity: Verbosity,

    cache: FastHashMap<Revision, ChangesetData>,

}

#[derive(Copy, Clone)]

struct Include {

    user: bool,

    number: bool,

    changeset: bool,

    date: bool,

    file: bool,

    line_number: bool,

}

impl Include {

    fn count(&self) -> usize {

        // Rust guarantees false is 0 and true is 1.

        self.user as usize

            + self.number as usize

            + self.changeset as usize

            + self.date as usize

            + self.file as usize

            + self.line_number as usize

    }

}

#[derive(Copy, Clone)]

enum Verbosity {

    Quiet,

    Default,

    Verbose,

}

#[derive(Default)]

struct ChangesetData {

    user: Option<Vec<u8>>,

    changeset: Option<Vec<u8>>,

    date: Option<Vec<u8>>,

}

impl ChangesetData {

    fn create(

        revision: Revision,

        changelog: &Changelog,

        include: Include,

        verbosity: Verbosity,

    ) -> Result<ChangesetData, CommandError> {

        let mut result = ChangesetData::default();

        if !(include.user || include.changeset || include.date) {

            return Ok(result);

        }

        let entry = changelog.entry(revision)?;

        let data = entry.data()?;

        if include.user {

            let user = match verbosity {

                Verbosity::Verbose => data.user(),

                _ => hg::utils::strings::short_user(data.user()),

            };

            result.user = Some(user.to_vec());

        }

        if include.changeset {

            let changeset = entry.as_revlog_entry().node().short();

            result.changeset = Some(format!("{:x}", changeset).into_bytes());

        }

        if include.date {

            let date = data.timestamp()?.format(match verbosity {

                Verbosity::Quiet => "%Y-%m-%d",

                _ => "%a %b %d %H:%M:%S %Y %z",

            });

            result.date = Some(format!("{}", date).into_bytes());

        }

        Ok(result)

    }

}

impl<'a> Formatter<'a> {

    fn new(

        changelog: &'a Changelog,

        encoder: &'a Encoder,

        include: Include,

        verbosity: Verbosity,

    ) -> Self {

        let cache = FastHashMap::default();

        Self {

            changelog,

            encoder,

            include,

            verbosity,

            cache,

        }

    }

    fn format(

        &mut self,

        annotations: Vec<ChangesetAnnotation>,

    ) -> Result<Vec<Vec<u8>>, CommandError> {

        let mut lines: Vec<Vec<Vec<u8>>> =

            Vec::with_capacity(annotations.len());

        let num_fields = self.include.count();

        let mut widths = vec![0usize; num_fields];

        for annotation in annotations {

            let revision = annotation.revision;

            let data = match self.cache.entry(revision) {

                Entry::Occupied(occupied) => occupied.into_mut(),

                Entry::Vacant(vacant) => vacant.insert(ChangesetData::create(

                    revision,

                    self.changelog,

                    self.include,

                    self.verbosity,

                )?),

            };

            let mut fields = Vec::with_capacity(num_fields);

            if let Some(user) = &data.user {

                fields.push(user.clone());

            }

            if self.include.number {

                fields.push(format_bytes!(b"{}", revision));

            }

            if let Some(changeset) = &data.changeset {

                fields.push(changeset.clone());

            }

            if let Some(date) = &data.date {

                fields.push(date.clone());

            }

            if self.include.file {

                fields.push(annotation.path.into_vec());

            }

            if self.include.line_number {

                fields.push(format_bytes!(b"{}", annotation.line_number));

            }

            for (field, width) in fields.iter().zip(widths.iter_mut()) {

                *width = std::cmp::max(

                    *width,

                    self.encoder.column_width_bytes(field),

                );

            }

            lines.push(fields);

        }

        let total_width = widths.iter().sum::<usize>() + num_fields - 1;

        Ok(lines

            .iter()

            .map(|fields| {

                let mut bytes = Vec::with_capacity(total_width);

                for (i, (field, width)) in

                    fields.iter().zip(widths.iter()).enumerate()

                {

                    if i > 0 {

                        let colon =

                            self.include.line_number && i == num_fields - 1;

                        bytes.push(if colon { b':' } else { b' ' });

                    }

                    let padding =

                        width - self.encoder.column_width_bytes(field);

                    bytes.resize(bytes.len() + padding, b' ');

                    bytes.extend_from_slice(field);

                }

                bytes

            })

            .collect())

    }

}