import 'dart:ffi';
import 'package:libgit2dart/libgit2dart.dart';
import 'bindings/libgit2_bindings.dart';
import 'bindings/tree.dart' as bindings;
import 'bindings/diff.dart' as diff_bindings;

class Tree {
  /// Initializes a new instance of [Tree] class from provided pointer to
  /// tree object in memory.
  ///
  /// Should be freed to release allocated memory.
  Tree(this._treePointer);

  /// Lookups a tree object for provided [id] in a [repo]sitory.
  ///
  /// Should be freed to release allocated memory.
  Tree.lookup({required Repository repo, required Oid id}) {
    _treePointer = bindings.lookup(
      repoPointer: repo.pointer,
      oidPointer: id.pointer,
    );
  }

  late final Pointer<git_tree> _treePointer;

  /// Pointer to memory address for allocated tree object.
  Pointer<git_tree> get pointer => _treePointer;

  /// Returns a list with tree entries of a tree.
  List<TreeEntry> get entries {
    final entryCount = bindings.entryCount(_treePointer);
    var result = <TreeEntry>[];
    for (var i = 0; i < entryCount; i++) {
      result.add(TreeEntry(bindings.getByIndex(
        treePointer: _treePointer,
        index: i,
      )));
    }

    return result;
  }

  /// Looksup a tree entry in the tree.
  ///
  /// If integer [value] is provided, lookup is done by entry position in the tree.
  ///
  /// If string [value] is provided, lookup is done by entry filename.
  ///
  /// If provided string [value] is a path to file, lookup is done by path.
  TreeEntry operator [](Object value) {
    if (value is int) {
      return TreeEntry(bindings.getByIndex(
        treePointer: _treePointer,
        index: value,
      ));
    } else if (value is String && value.contains('/')) {
      return TreeEntry(bindings.getByPath(
        rootPointer: _treePointer,
        path: value,
      ));
    } else if (value is String) {
      return TreeEntry(bindings.getByName(
        treePointer: _treePointer,
        filename: value,
      ));
    } else {
      throw ArgumentError.value(
          '$value should be either index position, filename or path');
    }
  }

  /// Returns the Oid of a tree.
  Oid get id => Oid(bindings.id(_treePointer));

  /// Get the number of entries listed in a tree.
  int get length => bindings.entryCount(_treePointer);

  /// Creates a diff between a tree and the working directory.
  ///
  /// Throws a [LibGit2Error] if error occured.
  Diff diffToWorkdir({
    Set<GitDiff> flags = const {GitDiff.normal},
    int contextLines = 3,
    int interhunkLines = 0,
  }) {
    return Diff(diff_bindings.treeToWorkdir(
      repoPointer: bindings.owner(_treePointer),
      treePointer: _treePointer,
      flags: flags.fold(0, (acc, e) => acc | e.value),
      contextLines: contextLines,
      interhunkLines: interhunkLines,
    ));
  }

  /// Creates a diff between a tree and repository index.
  ///
  /// Throws a [LibGit2Error] if error occured.
  Diff diffToIndex({
    required Index index,
    Set<GitDiff> flags = const {GitDiff.normal},
    int contextLines = 3,
    int interhunkLines = 0,
  }) {
    return Diff(diff_bindings.treeToIndex(
      repoPointer: bindings.owner(_treePointer),
      treePointer: _treePointer,
      indexPointer: index.pointer,
      flags: flags.fold(0, (acc, e) => acc | e.value),
      contextLines: contextLines,
      interhunkLines: interhunkLines,
    ));
  }

  /// Creates a diff with the difference between two tree objects.
  ///
  /// Throws a [LibGit2Error] if error occured.
  Diff diffToTree({
    required Tree tree,
    Set<GitDiff> flags = const {GitDiff.normal},
    int contextLines = 3,
    int interhunkLines = 0,
  }) {
    return Diff(diff_bindings.treeToTree(
      repoPointer: bindings.owner(_treePointer),
      oldTreePointer: _treePointer,
      newTreePointer: tree.pointer,
      flags: flags.fold(0, (acc, e) => acc | e.value),
      contextLines: contextLines,
      interhunkLines: interhunkLines,
    ));
  }

  /// Releases memory allocated for tree object.
  void free() => bindings.free(_treePointer);
}

class TreeEntry {
  /// Initializes a new instance of [TreeEntry] class.
  const TreeEntry(this._treeEntryPointer);

  /// Pointer to memory address for allocated tree entry object.
  final Pointer<git_tree_entry> _treeEntryPointer;

  /// Returns the Oid of the object pointed by the entry.
  Oid get id => Oid(bindings.entryId(_treeEntryPointer));

  /// Returns the filename of a tree entry.
  String get name => bindings.entryName(_treeEntryPointer);

  /// Returns the UNIX file attributes of a tree entry.
  GitFilemode get filemode {
    final modeInt = bindings.entryFilemode(_treeEntryPointer);
    return GitFilemode.values.singleWhere((mode) => modeInt == mode.value);
  }

  @override
  bool operator ==(other) {
    return (other is TreeEntry) &&
        (bindings.compare(
                aPointer: _treeEntryPointer,
                bPointer: other._treeEntryPointer) ==
            0);
  }

  bool operator <(other) {
    return (other is TreeEntry) &&
        (bindings.compare(
                aPointer: _treeEntryPointer,
                bPointer: other._treeEntryPointer) ==
            -1);
  }

  bool operator <=(other) {
    return (other is TreeEntry) &&
        (bindings.compare(
                aPointer: _treeEntryPointer,
                bPointer: other._treeEntryPointer) ==
            -1);
  }

  bool operator >(other) {
    return (other is TreeEntry) &&
        (bindings.compare(
                aPointer: _treeEntryPointer,
                bPointer: other._treeEntryPointer) ==
            1);
  }

  bool operator >=(other) {
    return (other is TreeEntry) &&
        (bindings.compare(
                aPointer: _treeEntryPointer,
                bPointer: other._treeEntryPointer) ==
            1);
  }

  @override
  int get hashCode => _treeEntryPointer.address.hashCode;

  /// Releases memory allocated for tree entry object.
  void free() => bindings.entryFree(_treeEntryPointer);

  @override
  String toString() => 'TreeEntry{id: $id, name: $name}';
}