// revlog.rs

//

// Copyright 2019-2020 Georges Racinet <georges.racinet@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 crate::{

    cindex,

    utils::{node_from_py_bytes, node_from_py_object},

};

use cpython::{

    exc::{IndexError, ValueError},

    ObjectProtocol, PyBytes, PyClone, PyDict, PyErr, PyModule, PyObject,

    PyResult, PyString, PyTuple, Python, PythonObject, ToPyObject,

};

use hg::{

    nodemap::{NodeMapError, NodeTree},

    revlog::{nodemap::NodeMap, RevlogIndex},

    NodeError, Revision,

};

use std::cell::RefCell;

/// Return a Struct implementing the Graph trait

pub(crate) fn pyindex_to_graph(

    py: Python,

    index: PyObject,

) -> PyResult<cindex::Index> {

    match index.extract::<MixedIndex>(py) {

        Ok(midx) => Ok(midx.clone_cindex(py)),

        Err(_) => cindex::Index::new(py, index),

    }

}

py_class!(pub class MixedIndex |py| {

    data cindex: RefCell<cindex::Index>;

    data nt: RefCell<Option<NodeTree>>;

    def __new__(_cls, cindex: PyObject) -> PyResult<MixedIndex> {

        Self::new(py, cindex)

    }

    /// Compatibility layer used for Python consumers needing access to the C index

    ///

    /// Only use case so far is `scmutil.shortesthexnodeidprefix`,

    /// that may need to build a custom `nodetree`, based on a specified revset.

    /// With a Rust implementation of the nodemap, we will be able to get rid of

    /// this, by exposing our own standalone nodemap class,

    /// ready to accept `MixedIndex`.

    def get_cindex(&self) -> PyResult<PyObject> {

        Ok(self.cindex(py).borrow().inner().clone_ref(py))

    }

    // Index API involving nodemap, as defined in mercurial/pure/parsers.py

    /// Return Revision if found, raises a bare `error.RevlogError`

    /// in case of ambiguity, same as C version does

    def get_rev(&self, node: PyBytes) -> PyResult<Option<Revision>> {

        let opt = self.get_nodetree(py)?.borrow();

        let nt = opt.as_ref().unwrap();

        let idx = &*self.cindex(py).borrow();

        let node = node_from_py_bytes(py, &node)?;

        nt.find_bin(idx, (&node).into()).map_err(|e| nodemap_error(py, e))

    }

    /// same as `get_rev()` but raises a bare `error.RevlogError` if node

    /// is not found.

    ///

    /// No need to repeat `node` in the exception, `mercurial/revlog.py`

    /// will catch and rewrap with it

    def rev(&self, node: PyBytes) -> PyResult<Revision> {

        self.get_rev(py, node)?.ok_or_else(|| revlog_error(py))

    }

    /// return True if the node exist in the index

    def has_node(&self, node: PyBytes) -> PyResult<bool> {

        self.get_rev(py, node).map(|opt| opt.is_some())

    }

    /// find length of shortest hex nodeid of a binary ID

    def shortest(&self, node: PyBytes) -> PyResult<usize> {

        let opt = self.get_nodetree(py)?.borrow();

        let nt = opt.as_ref().unwrap();

        let idx = &*self.cindex(py).borrow();

        match nt.unique_prefix_len_node(idx, &node_from_py_bytes(py, &node)?)

        {

            Ok(Some(l)) => Ok(l),

            Ok(None) => Err(revlog_error(py)),

            Err(e) => Err(nodemap_error(py, e)),

        }

    }

    def partialmatch(&self, node: PyObject) -> PyResult<Option<PyBytes>> {

        let opt = self.get_nodetree(py)?.borrow();

        let nt = opt.as_ref().unwrap();

        let idx = &*self.cindex(py).borrow();

        let node_as_string = if cfg!(feature = "python3-sys") {

            node.cast_as::<PyString>(py)?.to_string(py)?.to_string()

        }

        else {

            let node = node.extract::<PyBytes>(py)?;

            String::from_utf8_lossy(node.data(py)).to_string()

        };

        nt.find_hex(idx, &node_as_string)

            // TODO make an inner API returning the node directly

            .map(|opt| opt.map(

                |rev| PyBytes::new(py, idx.node(rev).unwrap().as_bytes())))

            .map_err(|e| nodemap_error(py, e))

    }

    /// append an index entry

    def append(&self, tup: PyTuple) -> PyResult<PyObject> {

        if tup.len(py) < 8 {

            // this is better than the panic promised by tup.get_item()

            return Err(

                PyErr::new::<IndexError, _>(py, "tuple index out of range"))

        }

        let node_bytes = tup.get_item(py, 7).extract(py)?;

        let node = node_from_py_object(py, &node_bytes)?;

        let mut idx = self.cindex(py).borrow_mut();

        let rev = idx.len() as Revision;

        idx.append(py, tup)?;

        self.get_nodetree(py)?.borrow_mut().as_mut().unwrap()

            .insert(&*idx, &node, rev)

            .map_err(|e| nodemap_error(py, e))?;

        Ok(py.None())

    }

    def __delitem__(&self, key: PyObject) -> PyResult<()> {

        // __delitem__ is both for `del idx[r]` and `del idx[r1:r2]`

        self.cindex(py).borrow().inner().del_item(py, key)?;

        let mut opt = self.get_nodetree(py)?.borrow_mut();

        let mut nt = opt.as_mut().unwrap();

        nt.invalidate_all();

        self.fill_nodemap(py, &mut nt)?;

        Ok(())

    }

    //

    // Reforwarded C index API

    //

    // index_methods (tp_methods). Same ordering as in revlog.c

    /// return the gca set of the given revs

    def ancestors(&self, *args, **kw) -> PyResult<PyObject> {

        self.call_cindex(py, "ancestors", args, kw)

    }

    /// return the heads of the common ancestors of the given revs

    def commonancestorsheads(&self, *args, **kw) -> PyResult<PyObject> {

        self.call_cindex(py, "commonancestorsheads", args, kw)

    }

    /// clear the index caches

    def clearcaches(&self, *args, **kw) -> PyResult<PyObject> {

        self.call_cindex(py, "clearcaches", args, kw)

    }

    /// get an index entry

    def get(&self, *args, **kw) -> PyResult<PyObject> {

        self.call_cindex(py, "get", args, kw)

    }

    /// compute phases

    def computephasesmapsets(&self, *args, **kw) -> PyResult<PyObject> {

        self.call_cindex(py, "computephasesmapsets", args, kw)

    }

    /// reachableroots

    def reachableroots2(&self, *args, **kw) -> PyResult<PyObject> {

        self.call_cindex(py, "reachableroots2", args, kw)

    }

    /// get head revisions

    def headrevs(&self, *args, **kw) -> PyResult<PyObject> {

        self.call_cindex(py, "headrevs", args, kw)

    }

    /// get filtered head revisions

    def headrevsfiltered(&self, *args, **kw) -> PyResult<PyObject> {

        self.call_cindex(py, "headrevsfiltered", args, kw)

    }

    /// True if the object is a snapshot

    def issnapshot(&self, *args, **kw) -> PyResult<PyObject> {

        self.call_cindex(py, "issnapshot", args, kw)

    }

    /// Gather snapshot data in a cache dict

    def findsnapshots(&self, *args, **kw) -> PyResult<PyObject> {

        self.call_cindex(py, "findsnapshots", args, kw)

    }

    /// determine revisions with deltas to reconstruct fulltext

    def deltachain(&self, *args, **kw) -> PyResult<PyObject> {

        self.call_cindex(py, "deltachain", args, kw)

    }

    /// slice planned chunk read to reach a density threshold

    def slicechunktodensity(&self, *args, **kw) -> PyResult<PyObject> {

        self.call_cindex(py, "slicechunktodensity", args, kw)

    }

    /// stats for the index

    def stats(&self, *args, **kw) -> PyResult<PyObject> {

        self.call_cindex(py, "stats", args, kw)

    }

    // index_sequence_methods and index_mapping_methods.

    //

    // Since we call back through the high level Python API,

    // there's no point making a distinction between index_get

    // and index_getitem.

    def __len__(&self) -> PyResult<usize> {

        self.cindex(py).borrow().inner().len(py)

    }

    def __getitem__(&self, key: PyObject) -> PyResult<PyObject> {

        // this conversion seems needless, but that's actually because

        // `index_getitem` does not handle conversion from PyLong,

        // which expressions such as [e for e in index] internally use.

        // Note that we don't seem to have a direct way to call

        // PySequence_GetItem (does the job), which would be better for

        // for performance

        let key = match key.extract::<Revision>(py) {

            Ok(rev) => rev.to_py_object(py).into_object(),

            Err(_) => key,

        };

        self.cindex(py).borrow().inner().get_item(py, key)

    }

    def __setitem__(&self, key: PyObject, value: PyObject) -> PyResult<()> {

        self.cindex(py).borrow().inner().set_item(py, key, value)

    }

    def __contains__(&self, item: PyObject) -> PyResult<bool> {

        // ObjectProtocol does not seem to provide contains(), so

        // this is an equivalent implementation of the index_contains()

        // defined in revlog.c

        let cindex = self.cindex(py).borrow();

        match item.extract::<Revision>(py) {

            Ok(rev) => {

                Ok(rev >= -1 && rev < cindex.inner().len(py)? as Revision)

            }

            Err(_) => {

                cindex.inner().call_method(

                    py,

                    "has_node",

                    PyTuple::new(py, &[item]),

                    None)?

                .extract(py)

            }

        }

    }

});

impl MixedIndex {

    fn new(py: Python, cindex: PyObject) -> PyResult<MixedIndex> {

        Self::create_instance(

            py,

            RefCell::new(cindex::Index::new(py, cindex)?),

            RefCell::new(None),

        )

    }

    /// This is scaffolding at this point, but it could also become

    /// a way to start a persistent nodemap or perform a

    /// vacuum / repack operation

    fn fill_nodemap(

        &self,

        py: Python,

        nt: &mut NodeTree,

    ) -> PyResult<PyObject> {

        let index = self.cindex(py).borrow();

        for r in 0..index.len() {

            let rev = r as Revision;

            // in this case node() won't ever return None

            nt.insert(&*index, index.node(rev).unwrap(), rev)

                .map_err(|e| nodemap_error(py, e))?

        }

        Ok(py.None())

    }

    fn get_nodetree<'a>(

        &'a self,

        py: Python<'a>,

    ) -> PyResult<&'a RefCell<Option<NodeTree>>> {

        if self.nt(py).borrow().is_none() {

            let readonly = Box::new(Vec::new());

            let mut nt = NodeTree::load_bytes(readonly, 0);

            self.fill_nodemap(py, &mut nt)?;

            self.nt(py).borrow_mut().replace(nt);

        }

        Ok(self.nt(py))

    }

    /// forward a method call to the underlying C index

    fn call_cindex(

        &self,

        py: Python,

        name: &str,

        args: &PyTuple,

        kwargs: Option<&PyDict>,

    ) -> PyResult<PyObject> {

        self.cindex(py)

            .borrow()

            .inner()

            .call_method(py, name, args, kwargs)

    }

    pub fn clone_cindex(&self, py: Python) -> cindex::Index {

        self.cindex(py).borrow().clone_ref(py)