// debugdata.rs
//
// Copyright 2020 Antoine Cezar <antoine.cezar@octobus.net>
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.

use std::path::Path;

use crate::revlog::revlog::{Revlog, RevlogError};
use crate::revlog::NodePrefix;
use crate::revlog::Revision;

/// Kind of data to debug
#[derive(Debug, Copy, Clone)]
pub enum DebugDataKind {
    Changelog,
    Manifest,
}

/// Kind of error encountered by DebugData
#[derive(Debug)]
pub enum DebugDataErrorKind {
    /// Error when reading a `revlog` file.
    IoError(std::io::Error),
    /// The revision has not been found.
    InvalidRevision,
    /// Found more than one revision whose ID match the requested prefix
    AmbiguousPrefix,
    /// A `revlog` file is corrupted.
    CorruptedRevlog,
    /// The `revlog` format version is not supported.
    UnsuportedRevlogVersion(u16),
    /// The `revlog` data format is not supported.
    UnknowRevlogDataFormat(u8),
}

/// A DebugData error
#[derive(Debug)]
pub struct DebugDataError {
    /// Kind of error encountered by DebugData
    pub kind: DebugDataErrorKind,
}

impl From<DebugDataErrorKind> for DebugDataError {
    fn from(kind: DebugDataErrorKind) -> Self {
        DebugDataError { kind }
    }
}

impl From<std::io::Error> for DebugDataError {
    fn from(err: std::io::Error) -> Self {
        let kind = DebugDataErrorKind::IoError(err);
        DebugDataError { kind }
    }
}

impl From<RevlogError> for DebugDataError {
    fn from(err: RevlogError) -> Self {
        match err {
            RevlogError::IoError(err) => DebugDataErrorKind::IoError(err),
            RevlogError::UnsuportedVersion(version) => {
                DebugDataErrorKind::UnsuportedRevlogVersion(version)
            }
            RevlogError::InvalidRevision => {
                DebugDataErrorKind::InvalidRevision
            }
            RevlogError::AmbiguousPrefix => {
                DebugDataErrorKind::AmbiguousPrefix
            }
            RevlogError::Corrupted => DebugDataErrorKind::CorruptedRevlog,
            RevlogError::UnknowDataFormat(format) => {
                DebugDataErrorKind::UnknowRevlogDataFormat(format)
            }
        }
        .into()
    }
}

/// Dump the contents data of a revision.
pub fn debug_data(
    root: &Path,
    rev: &str,
    kind: DebugDataKind,
) -> Result<Vec<u8>, DebugDataError> {
    let index_file = match kind {
        DebugDataKind::Changelog => root.join(".hg/store/00changelog.i"),
        DebugDataKind::Manifest => root.join(".hg/store/00manifest.i"),
    };
    let revlog = Revlog::open(&index_file, None)?;

    let data = match rev.parse::<Revision>() {
        Ok(rev) => revlog.get_rev_data(rev)?,
        _ => {
            let node = NodePrefix::from_hex(&rev)
                .map_err(|_| DebugDataErrorKind::InvalidRevision)?;
            let rev = revlog.get_node_rev(node.borrow())?;
            revlog.get_rev_data(rev)?
        }
    };

    Ok(data)
}