use crate::errors::HgError;

use bitflags::bitflags;

use std::convert::TryFrom;

#[derive(Copy, Clone, Debug, Eq, PartialEq)]

pub enum EntryState {

    Normal,

    Added,

    Removed,

    Merged,

}

/// The C implementation uses all signed types. This will be an issue

/// either when 4GB+ source files are commonplace or in 2038, whichever

/// comes first.

#[derive(Debug, PartialEq, Copy, Clone)]

pub struct DirstateEntry {

    flags: Flags,

    mode: i32,

    size: i32,

    mtime: i32,

}

bitflags! {

        const WDIR_TRACKED = 1 << 0;

        const P1_TRACKED = 1 << 1;

        const P2_TRACKED = 1 << 2;

        const POSSIBLY_DIRTY = 1 << 3;

        const MERGED = 1 << 4;

        const CLEAN_P1 = 1 << 5;

        const CLEAN_P2 = 1 << 6;

        const ENTRYLESS_TREE_NODE = 1 << 7;

    }

}

pub const V1_RANGEMASK: i32 = 0x7FFFFFFF;

pub const MTIME_UNSET: i32 = -1;

/// A `DirstateEntry` with a size of `-2` means that it was merged from the

/// other parent. This allows revert to pick the right status back during a

/// merge.

pub const SIZE_FROM_OTHER_PARENT: i32 = -2;

/// A special value used for internal representation of special case in

/// dirstate v1 format.

pub const SIZE_NON_NORMAL: i32 = -1;

impl DirstateEntry {

    pub fn from_v1_data(

        state: EntryState,

        mode: i32,

        size: i32,

        mtime: i32,

    ) -> Self {

        match state {

            EntryState::Normal => {

                if size == SIZE_FROM_OTHER_PARENT {

                    Self::new_from_p2()

                } else if size == SIZE_NON_NORMAL {

                    Self::new_possibly_dirty()

                } else if mtime == MTIME_UNSET {

                    Self {

                        flags: Flags::WDIR_TRACKED

                            | Flags::P1_TRACKED

                            | Flags::POSSIBLY_DIRTY,

                        mode,

                        size,

                        mtime: 0,

                    }

                } else {

                    Self {

                        flags: Flags::WDIR_TRACKED | Flags::P1_TRACKED,

                        mode,

                        size,

                        mtime,

                    }

                }

            }

            EntryState::Added => Self::new_added(),

            EntryState::Removed => Self {

                flags: if size == SIZE_NON_NORMAL {

                    Flags::P1_TRACKED // might not be true because of rename ?

                    | Flags::P2_TRACKED // might not be true because of rename ?

                    | Flags::MERGED

                } else if size == SIZE_FROM_OTHER_PARENT {

                    // We don’t know if P1_TRACKED should be set (file history)

                    Flags::P2_TRACKED | Flags::CLEAN_P2

                } else {

                    Flags::P1_TRACKED

                },

                mode: 0,

                size: 0,

                mtime: 0,

            },

            EntryState::Merged => Self::new_merged(),

        }

    }

    fn new_from_p2() -> Self {

        Self {

            // might be missing P1_TRACKED

            flags: Flags::WDIR_TRACKED | Flags::P2_TRACKED | Flags::CLEAN_P2,

            mode: 0,

            size: SIZE_FROM_OTHER_PARENT,

            mtime: MTIME_UNSET,

        }

    }

    fn new_possibly_dirty() -> Self {

        Self {

            flags: Flags::WDIR_TRACKED

                | Flags::P1_TRACKED

                | Flags::POSSIBLY_DIRTY,

            mode: 0,

            size: SIZE_NON_NORMAL,

            mtime: MTIME_UNSET,

        }

    }

    fn new_added() -> Self {

        Self {

            flags: Flags::WDIR_TRACKED,

            mode: 0,

            size: SIZE_NON_NORMAL,

            mtime: MTIME_UNSET,

        }

    }

    fn new_merged() -> Self {

        Self {

            flags: Flags::WDIR_TRACKED

                | Flags::P1_TRACKED // might not be true because of rename ?

                | Flags::P2_TRACKED // might not be true because of rename ?

                | Flags::MERGED,

            mode: 0,

            size: SIZE_NON_NORMAL,

            mtime: MTIME_UNSET,

        }

    }

    /// Creates a new entry in "removed" state.

    ///

    /// `size` is expected to be zero, `SIZE_NON_NORMAL`, or

    /// `SIZE_FROM_OTHER_PARENT`

    pub fn new_removed(size: i32) -> Self {

        Self::from_v1_data(EntryState::Removed, 0, size, 0)

    }

    /// TODO: refactor `DirstateMap::add_file` to not take a `DirstateEntry`

    /// parameter and remove this constructor

    pub fn new_for_add_file(mode: i32, size: i32, mtime: i32) -> Self {

        // XXX Arbitrary default value since the value is determined later

        let state = EntryState::Normal;

        Self::from_v1_data(state, mode, size, mtime)

    }

    fn tracked_in_any_parent(&self) -> bool {

        self.flags.intersects(Flags::P1_TRACKED | Flags::P2_TRACKED)

    }

        self.tracked_in_any_parent()

            && !self.flags.contains(Flags::WDIR_TRACKED)

    }

        self.removed() && self.flags.contains(Flags::MERGED)

    }

        self.removed() && self.flags.contains(Flags::CLEAN_P2)

    }

        self.flags.contains(Flags::WDIR_TRACKED | Flags::MERGED)

    }

        self.flags.contains(Flags::WDIR_TRACKED)

            && !self.tracked_in_any_parent()

    }

        self.flags.contains(Flags::WDIR_TRACKED | Flags::CLEAN_P2)

    }

    pub fn state(&self) -> EntryState {

        if self.removed() {

            EntryState::Removed

        } else if self.merged() {

            EntryState::Merged

        } else if self.added() {

            EntryState::Added

        } else {

            EntryState::Normal

        }

    }

    pub fn mode(&self) -> i32 {

        self.mode

    }

    pub fn size(&self) -> i32 {

        if self.merged_removed() {

            SIZE_NON_NORMAL

        } else if self.from_p2_removed() {

            SIZE_FROM_OTHER_PARENT

        } else if self.removed() {

            0

        } else if self.merged() {

            SIZE_FROM_OTHER_PARENT

        } else if self.added() {

            SIZE_NON_NORMAL

        } else if self.from_p2() {

            SIZE_FROM_OTHER_PARENT

        } else if self.flags.contains(Flags::POSSIBLY_DIRTY) {

            self.size // TODO: SIZE_NON_NORMAL ?

        } else {

            self.size

        }

    }

    pub fn mtime(&self) -> i32 {

        if self.removed() {

            0

        } else if self.flags.contains(Flags::POSSIBLY_DIRTY) {

            MTIME_UNSET

        } else if self.merged() {

            MTIME_UNSET

        } else if self.added() {

            MTIME_UNSET

        } else if self.from_p2() {

            MTIME_UNSET

        } else {

            self.mtime

        }

    }

    /// Returns `(state, mode, size, mtime)` for the puprose of serialization

    /// in the dirstate-v1 format.

    ///

    /// This includes marker values such as `mtime == -1`. In the future we may

    /// want to not represent these cases that way in memory, but serialization

    /// will need to keep the same format.

    pub fn v1_data(&self) -> (u8, i32, i32, i32) {

        (self.state().into(), self.mode(), self.size(), self.mtime())

    }

    pub fn is_non_normal(&self) -> bool {

        self.state() != EntryState::Normal || self.mtime() == MTIME_UNSET

    }

    pub fn is_from_other_parent(&self) -> bool {

        self.state() == EntryState::Normal

            && self.size() == SIZE_FROM_OTHER_PARENT

    }

    // TODO: other platforms

    #[cfg(unix)]

    pub fn mode_changed(

        &self,

        filesystem_metadata: &std::fs::Metadata,

    ) -> bool {

        use std::os::unix::fs::MetadataExt;

        const EXEC_BIT_MASK: u32 = 0o100;

        let dirstate_exec_bit = (self.mode() as u32) & EXEC_BIT_MASK;

        let fs_exec_bit = filesystem_metadata.mode() & EXEC_BIT_MASK;

        dirstate_exec_bit != fs_exec_bit

    }

    /// Returns a `(state, mode, size, mtime)` tuple as for

    /// `DirstateMapMethods::debug_iter`.

    pub fn debug_tuple(&self) -> (u8, i32, i32, i32) {

        let state = if self.flags.contains(Flags::ENTRYLESS_TREE_NODE) {

            b' '

        } else {

            self.state().into()

        };

        (state, self.mode(), self.size(), self.mtime())

    }

    pub fn mtime_is_ambiguous(&self, now: i32) -> bool {

        self.state() == EntryState::Normal && self.mtime() == now

    }

    pub fn clear_ambiguous_mtime(&mut self, now: i32) -> bool {

        let ambiguous = self.mtime_is_ambiguous(now);

        if ambiguous {

            // The file was last modified "simultaneously" with the current

            // write to dirstate (i.e. within the same second for file-

            // systems with a granularity of 1 sec). This commonly happens

            // for at least a couple of files on 'update'.

            // The user could change the file without changing its size

            // within the same second. Invalidate the file's mtime in

            // dirstate, forcing future 'status' calls to compare the

            // contents of the file if the size is the same. This prevents

            // mistakenly treating such files as clean.

            self.clear_mtime()

        }

        ambiguous

    }