// parsers.rs

//

// Copyright 2019 Raphaël Gomès <rgomes@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.

//! Bindings for the `hg::dirstate::parsers` module provided by the

//! `hg-core` package.

//!

//! From Python, this will be seen as `mercurial.rustext.parsers`

//!

use cpython::{

    exc, PyBytes, PyDict, PyErr, PyInt, PyModule, PyResult, PyTuple, Python,

    PythonObject, ToPyObject,

};

use hg::{

    pack_dirstate, parse_dirstate, utils::hg_path::HgPathBuf, DirstateEntry,

    DirstatePackError, DirstateParents, DirstateParseError, PARENT_SIZE,

};

use std::collections::HashMap;

use std::convert::TryInto;

use libc::c_char;

use crate::dirstate::{decapsule_make_dirstate_tuple, extract_dirstate};

use std::time::Duration;

fn parse_dirstate_wrapper(

    py: Python,

    dmap: PyDict,

    copymap: PyDict,

    st: PyBytes,

) -> PyResult<PyTuple> {

    let mut dirstate_map = HashMap::new();

    let mut copies = HashMap::new();

    match parse_dirstate(&mut dirstate_map, &mut copies, st.data(py)) {

        Ok(parents) => {

            for (filename, entry) in dirstate_map {

                // Explicitly go through u8 first, then cast to

                // platform-specific `c_char` because Into<u8> has a specific

                // implementation while `as c_char` would just do a naive enum

                // cast.

                let state: u8 = entry.state.into();

                dmap.set_item(

                    py,

                    PyBytes::new(py, filename.as_ref()),

                    decapsule_make_dirstate_tuple(py)?(

                        state as c_char,

                        entry.mode,

                        entry.size,

                        entry.mtime,

                    ),

                )?;

            }

            for (path, copy_path) in copies {

                copymap.set_item(

                    py,

                    PyBytes::new(py, path.as_ref()),

                    PyBytes::new(py, copy_path.as_ref()),

                )?;

            }

            Ok(

                (PyBytes::new(py, &parents.p1), PyBytes::new(py, &parents.p2))

                    .to_py_object(py),

            )

        }

        Err(e) => Err(PyErr::new::<exc::ValueError, _>(

            py,

            match e {

                DirstateParseError::TooLittleData => {

                    "too little data for parents".to_string()

                }

                DirstateParseError::Overflow => {

                    "overflow in dirstate".to_string()

                }

                DirstateParseError::CorruptedEntry(e) => e,

                DirstateParseError::Damaged => {

                    "dirstate appears to be damaged".to_string()

                }

            },

        )),

    }

}

fn pack_dirstate_wrapper(

    py: Python,

    dmap: PyDict,

    copymap: PyDict,

    pl: PyTuple,

    now: PyInt,

) -> PyResult<PyBytes> {

    let p1 = pl.get_item(py, 0).extract::<PyBytes>(py)?;

    let p1: &[u8] = p1.data(py);

    let p2 = pl.get_item(py, 1).extract::<PyBytes>(py)?;

    let p2: &[u8] = p2.data(py);

    let mut dirstate_map = extract_dirstate(py, &dmap)?;

    let copies: Result<HashMap<HgPathBuf, HgPathBuf>, PyErr> = copymap

        .items(py)

        .iter()

        .map(|(key, value)| {

            Ok((

                HgPathBuf::from_bytes(key.extract::<PyBytes>(py)?.data(py)),

                HgPathBuf::from_bytes(value.extract::<PyBytes>(py)?.data(py)),

            ))

        })

        .collect();

    if p1.len() != PARENT_SIZE || p2.len() != PARENT_SIZE {

        return Err(PyErr::new::<exc::ValueError, _>(

            py,

            "expected a 20-byte hash".to_string(),

        ));

    }

    match pack_dirstate(

        &mut dirstate_map,

        &copies?,

        DirstateParents {

            p1: p1.try_into().unwrap(),

            p2: p2.try_into().unwrap(),

        },

        Duration::from_secs(now.as_object().extract::<u64>(py)?),

    ) {

        Ok(packed) => {

            for (

                filename,

                DirstateEntry {

                    state,

                    mode,

                    size,

                    mtime,

                },

            ) in dirstate_map

            {

                // Explicitly go through u8 first, then cast to

                // platform-specific `c_char` because Into<u8> has a specific

                // implementation while `as c_char` would just do a naive enum

                // cast.

                let state: u8 = state.into();

                dmap.set_item(

                    py,

                    PyBytes::new(py, filename.as_ref()),

                    decapsule_make_dirstate_tuple(py)?(

                        state as c_char,

                        mode,

                        size,

                        mtime,

                    ),

                )?;

            }

            Ok(PyBytes::new(py, &packed))

        }

        Err(error) => Err(PyErr::new::<exc::ValueError, _>(

            py,

            match error {

                DirstatePackError::CorruptedParent => {

                    "expected a 20-byte hash".to_string()

                }

                DirstatePackError::CorruptedEntry(e) => e,

                DirstatePackError::BadSize(expected, actual) => {

                    format!("bad dirstate size: {} != {}", actual, expected)

                }

            },

        )),

    }

}

/// Create the module, with `__package__` given from parent

pub fn init_parsers_module(py: Python, package: &str) -> PyResult<PyModule> {

    let dotted_name = &format!("{}.parsers", package);

    let m = PyModule::new(py, dotted_name)?;

    m.add(py, "__package__", package)?;

    m.add(py, "__doc__", "Parsers - Rust implementation")?;

    m.add(

        py,

        "parse_dirstate",

        py_fn!(

            py,

            parse_dirstate_wrapper(dmap: PyDict, copymap: PyDict, st: PyBytes)

        ),

    )?;

    m.add(

        py,

        "pack_dirstate",

        py_fn!(

            py,

            pack_dirstate_wrapper(

                dmap: PyDict,

                copymap: PyDict,

                pl: PyTuple,

                now: PyInt

            )

        ),

    )?;

    let sys = PyModule::import(py, "sys")?;

    let sys_modules: PyDict = sys.get(py, "modules")?.extract(py)?;

    sys_modules.set_item(py, dotted_name, &m)?;

    Ok(m)

}