import 'dart:ffi';
import 'package:ffi/ffi.dart';
import '../error.dart';
import 'libgit2_bindings.dart';
import '../util.dart';

/// Update the contents of an existing index object in memory by reading from the hard disk.
///
/// If force is true, this performs a "hard" read that discards in-memory changes and
/// always reloads the on-disk index data. If there is no on-disk version,
/// the index will be cleared.
///
/// If force is false, this does a "soft" read that reloads the index data from disk only
/// if it has changed since the last time it was loaded. Purely in-memory index data
/// will be untouched. Be aware: if there are changes on disk, unwritten in-memory changes
/// are discarded.
///
/// Throws a [LibGit2Error] if error occured.
void read(Pointer<git_index> index, bool force) {
  final forceC = force == true ? 1 : 0;
  final error = libgit2.git_index_read(index, forceC);

  if (error < 0) {
    throw LibGit2Error(libgit2.git_error_last());
  }
}

/// Read a tree into the index file with stats.
///
/// The current index contents will be replaced by the specified tree.
///
/// Throws a [LibGit2Error] if error occured.
void readTree(Pointer<git_index> index, Pointer<git_tree> tree) {
  final error = libgit2.git_index_read_tree(index, tree);

  if (error < 0) {
    throw LibGit2Error(libgit2.git_error_last());
  }
}

/// Write the index as a tree.
///
/// This method will scan the index and write a representation of its current state back to disk;
/// it recursively creates tree objects for each of the subtrees stored in the index, but only
/// returns the OID of the root tree. This is the OID that can be used e.g. to create a commit.
///
/// The index instance cannot be bare, and needs to be associated to an existing repository.
///
/// The index must not contain any file in conflict.
///
/// Throws a [LibGit2Error] if error occured.
Pointer<git_oid> writeTree(Pointer<git_index> index) {
  final out = calloc<git_oid>();
  final error = libgit2.git_index_write_tree(out, index);

  if (error < 0) {
    throw LibGit2Error(libgit2.git_error_last());
  } else {
    return out;
  }
}

/// Write the index as a tree to the given repository.
///
/// This method will do the same as [writeTree], but letting the user choose the repository
/// where the tree will be written.
///
/// The index must not contain any file in conflict.
///
/// Throws a [LibGit2Error] if error occured.
Pointer<git_oid> writeTreeTo(
  Pointer<git_index> index,
  Pointer<git_repository> repo,
) {
  final out = calloc<git_oid>();
  final error = libgit2.git_index_write_tree_to(out, index, repo);

  if (error < 0) {
    throw LibGit2Error(libgit2.git_error_last());
  } else {
    return out;
  }
}

/// Find the first position of any entries which point to given path in the Git index.
bool find(Pointer<git_index> index, String path) {
  final pathC = path.toNativeUtf8().cast<Int8>();
  final result = libgit2.git_index_find(nullptr, index, pathC);

  calloc.free(pathC);

  return result == git_error_code.GIT_ENOTFOUND ? false : true;
}

/// Get the count of entries currently in the index.
int entryCount(Pointer<git_index> index) => libgit2.git_index_entrycount(index);

/// Get a pointer to one of the entries in the index based on position.
///
/// The entry is not modifiable and should not be freed.
///
/// Throws [RangeError] when provided index is outside of valid range.
Pointer<git_index_entry> getByIndex(Pointer<git_index> index, int n) {
  final result = libgit2.git_index_get_byindex(index, n);

  if (result == nullptr) {
    throw RangeError('Out of bounds');
  } else {
    return result;
  }
}

/// Get a pointer to one of the entries in the index based on path.
///
///The entry is not modifiable and should not be freed.
///
/// Throws [ArgumentError] if nothing found for provided path.
Pointer<git_index_entry> getByPath(
  Pointer<git_index> index,
  String path,
  int stage,
) {
  final pathC = path.toNativeUtf8().cast<Int8>();
  final result = libgit2.git_index_get_bypath(index, pathC, stage);

  calloc.free(pathC);

  if (result == nullptr) {
    throw ArgumentError.value('$path was not found');
  } else {
    return result;
  }
}

/// Clear the contents (all the entries) of an index object.
///
/// This clears the index object in memory; changes must be explicitly written to
/// disk for them to take effect persistently.
///
/// Throws a [LibGit2Error] if error occured.
void clear(Pointer<git_index> index) {
  final error = libgit2.git_index_clear(index);

  if (error < 0) {
    throw LibGit2Error(libgit2.git_error_last());
  }
}

/// Add or update an index entry from an in-memory struct.
///
/// If a previous index entry exists that has the same path and stage as the given `sourceEntry`,
/// it will be replaced. Otherwise, the `sourceEntry` will be added.
///
/// Throws a [LibGit2Error] if error occured.
void add(Pointer<git_index> index, Pointer<git_index_entry> sourceEntry) {
  final error = libgit2.git_index_add(index, sourceEntry);

  if (error < 0) {
    throw LibGit2Error(libgit2.git_error_last());
  }
}

/// Add or update an index entry from a file on disk.
///
/// The file path must be relative to the repository's working folder and must be readable.
///
/// This method will fail in bare index instances.
///
/// This forces the file to be added to the index, not looking at gitignore rules.
///
/// If this file currently is the result of a merge conflict, this file will no longer be
/// marked as conflicting. The data about the conflict will be moved to the "resolve undo"
/// (REUC) section.
///
/// Throws a [LibGit2Error] if error occured.
void addByPath(Pointer<git_index> index, String path) {
  final pathC = path.toNativeUtf8().cast<Int8>();
  final error = libgit2.git_index_add_bypath(index, pathC);

  calloc.free(pathC);

  if (error < 0) {
    throw LibGit2Error(libgit2.git_error_last());
  }
}

/// Add or update index entries matching files in the working directory.
///
/// This method will fail in bare index instances.
///
/// The `pathspec` is a list of file names or shell glob patterns that will be matched
/// against files in the repository's working directory. Each file that matches will be
/// added to the index (either updating an existing entry or adding a new entry).
///
/// Throws a [LibGit2Error] if error occured.
void addAll(Pointer<git_index> index, List<String> pathspec) {
  var pathspecC = calloc<git_strarray>();
  final List<Pointer<Int8>> pathPointers =
      pathspec.map((e) => e.toNativeUtf8().cast<Int8>()).toList();
  final Pointer<Pointer<Int8>> strArray = calloc(pathspec.length);

  for (var i = 0; i < pathspec.length; i++) {
    strArray[i] = pathPointers[i];
  }

  pathspecC.ref.strings = strArray;
  pathspecC.ref.count = pathspec.length;

  final error = libgit2.git_index_add_all(
    index,
    pathspecC,
    0,
    nullptr,
    nullptr,
  );

  calloc.free(pathspecC);
  for (var p in pathPointers) {
    calloc.free(p);
  }
  calloc.free(strArray);

  if (error < 0) {
    throw LibGit2Error(libgit2.git_error_last());
  }
}

/// Write an existing index object from memory back to disk using an atomic file lock.
///
/// Throws a [LibGit2Error] if error occured.
void write(Pointer<git_index> index) {
  final error = libgit2.git_index_write(index);

  if (error < 0) {
    throw LibGit2Error(libgit2.git_error_last());
  }
}

/// Remove an entry from the index.
///
/// Throws a [LibGit2Error] if error occured.
void remove(Pointer<git_index> index, String path, int stage) {
  final pathC = path.toNativeUtf8().cast<Int8>();
  final error = libgit2.git_index_remove(index, pathC, stage);

  calloc.free(pathC);

  if (error < 0) {
    throw LibGit2Error(libgit2.git_error_last());
  }
}

/// Remove all matching index entries.
///
/// Throws a [LibGit2Error] if error occured.
void removeAll(Pointer<git_index> index, List<String> pathspec) {
  final pathspecC = calloc<git_strarray>();
  final List<Pointer<Int8>> pathPointers =
      pathspec.map((e) => e.toNativeUtf8().cast<Int8>()).toList();
  final Pointer<Pointer<Int8>> strArray = calloc(pathspec.length);

  for (var i = 0; i < pathspec.length; i++) {
    strArray[i] = pathPointers[i];
  }

  pathspecC.ref.strings = strArray;
  pathspecC.ref.count = pathspec.length;

  final error = libgit2.git_index_remove_all(
    index,
    pathspecC,
    nullptr,
    nullptr,
  );

  calloc.free(pathspecC);
  for (var p in pathPointers) {
    calloc.free(p);
  }
  calloc.free(strArray);

  if (error < 0) {
    throw LibGit2Error(libgit2.git_error_last());
  }
}

/// Determine if the index contains entries representing file conflicts.
bool hasConflicts(Pointer<git_index> index) {
  return libgit2.git_index_has_conflicts(index) == 1 ? true : false;
}

/// Return list of conflicts in the index.
///
/// Throws a [LibGit2Error] if error occured.
List<Map<String, Pointer<git_index_entry>>> conflictList(
    Pointer<git_index> index) {
  final iterator = calloc<Pointer<git_index_conflict_iterator>>();
  final iteratorError =
      libgit2.git_index_conflict_iterator_new(iterator, index);

  if (iteratorError < 0) {
    throw LibGit2Error(libgit2.git_error_last());
  }

  var result = <Map<String, Pointer<git_index_entry>>>[];
  var error = 0;

  while (error >= 0) {
    final ancestorOut = calloc<Pointer<git_index_entry>>();
    final ourOut = calloc<Pointer<git_index_entry>>();
    final theirOut = calloc<Pointer<git_index_entry>>();
    error = libgit2.git_index_conflict_next(
      ancestorOut,
      ourOut,
      theirOut,
      iterator.value,
    );
    if (error >= 0) {
      result.add({
        'ancestor': ancestorOut.value,
        'our': ourOut.value,
        'their': theirOut.value,
      });
      calloc.free(ancestorOut);
      calloc.free(ourOut);
      calloc.free(theirOut);
    } else {
      break;
    }
  }

  libgit2.git_index_conflict_iterator_free(iterator.value);
  return result;
}

/// Removes the index entries that represent a conflict of a single file.
///
/// Throws a [LibGit2Error] if error occured.
void conflictRemove(Pointer<git_index> index, String path) {
  final pathC = path.toNativeUtf8().cast<Int8>();
  final error = libgit2.git_index_conflict_remove(index, pathC);

  calloc.free(pathC);

  if (error < 0) {
    throw LibGit2Error(libgit2.git_error_last());
  }
}

/// Get the repository this index relates to.
Pointer<git_repository> owner(Pointer<git_index> index) =>
    libgit2.git_index_owner(index);

/// Free an existing index object.
void free(Pointer<git_index> index) => libgit2.git_index_free(index);