/*
 * Copyright 2010-2024 The pygit2 contributors
 *
 * This file is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2,
 * as published by the Free Software Foundation.
 *
 * In addition to the permissions in the GNU General Public License,
 * the authors give you unlimited permission to link the compiled
 * version of this file into combinations with other programs,
 * and to distribute those combinations without any restriction
 * coming from the use of this file.  (The General Public License
 * restrictions do apply in other respects; for example, they cover
 * modification of the file, and distribution when not linked into
 * a combined executable.)
 *
 * This file is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; see the file COPYING.  If not, write to
 * the Free Software Foundation, 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#define PY_SSIZE_T_CLEAN
#include <Python.h>
#include <structmember.h>
#include "diff.h"
#include "error.h"
#include "object.h"
#include "oid.h"
#include "types.h"
#include "utils.h"

extern PyTypeObject DiffHunkType;
extern PyTypeObject BlobType;
PyTypeObject PatchType;


PyObject *
wrap_patch(git_patch *patch, Blob *oldblob, Blob *newblob)
{
    Patch *py_patch;

    assert(patch);

    py_patch = PyObject_New(Patch, &PatchType);
    if (py_patch) {
        py_patch->patch = patch;

        Py_XINCREF(oldblob);
        py_patch->oldblob = oldblob;

        Py_XINCREF(newblob);
        py_patch->newblob = newblob;
    }

    return (PyObject*) py_patch;
}

static void
Patch_dealloc(Patch *self)
{
    Py_CLEAR(self->oldblob);
    Py_CLEAR(self->newblob);
    git_patch_free(self->patch);
    PyObject_Del(self);
}

PyDoc_STRVAR(Patch_delta__doc__, "Get the delta associated with a patch.");

PyObject *
Patch_delta__get__(Patch *self)
{
    assert(self->patch);
    return wrap_diff_delta(git_patch_get_delta(self->patch));
}

PyDoc_STRVAR(Patch_line_stats__doc__,
    "Get line counts of each type in a patch (context, additions, deletions).");

PyObject *
Patch_line_stats__get__(Patch *self)
{
    size_t context, additions, deletions;
    int err;

    assert(self->patch);
    err = git_patch_line_stats(&context, &additions, &deletions, self->patch);
    if (err < 0)
        return Error_set(err);

    return Py_BuildValue("III", context, additions, deletions);
}

PyDoc_STRVAR(Patch_create_from__doc__,
    "Create a patch from blobs, buffers, or a blob and a buffer");

static PyObject *
Patch_create_from(PyObject *self, PyObject *args, PyObject *kwds)
{
  /* A generic wrapper around
   * git_patch_from_blob_and_buffer
   * git_patch_from_buffers
   * git_patch_from_blobs
   */
  git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
  git_patch *patch;
  char *old_as_path = NULL, *new_as_path = NULL;
  PyObject *oldobj = NULL, *newobj = NULL;
  Blob *oldblob = NULL, *newblob = NULL;
  const char *oldbuf = NULL, *newbuf = NULL;
  Py_ssize_t oldbuflen, newbuflen;
  int err;

  char *keywords[] = {"old", "new", "old_as_path", "new_as_path",
                      "flag", "context_lines", "interhunk_lines",
                      NULL};

  if (!PyArg_ParseTupleAndKeywords(args, kwds, "OO|zzIHH", keywords,
                                   &oldobj, &newobj, &old_as_path, &new_as_path,
                                   &opts.flags, &opts.context_lines,
                                   &opts.interhunk_lines))
    return NULL;

  if (oldobj != Py_None && PyObject_TypeCheck(oldobj, &BlobType))
  {
    /* The old object exists and is a blob */
    oldblob = (Blob*)oldobj;
    if (Object__load((Object*)oldblob) == NULL) { return NULL; } // Lazy load

    if (newobj != Py_None && PyObject_TypeCheck(newobj, &BlobType))
    {
      /* The new object exists and is a blob */
      newblob = (Blob*)newobj;
      if (Object__load((Object*)newblob) == NULL) { return NULL; } // Lazy load

      err = git_patch_from_blobs(&patch, oldblob->blob, old_as_path,
                                 newblob->blob, new_as_path, &opts);
    }
    else {
      /* The new object does not exist or is a buffer */
      if (!PyArg_Parse(newobj, "z#", &newbuf, &newbuflen))
        return NULL;

      err = git_patch_from_blob_and_buffer(&patch, oldblob->blob, old_as_path,
                                           newbuf, newbuflen, new_as_path,
                                           &opts);
    }
  }
  else
  {
    /* The old object does exist and is a buffer */
    if (!PyArg_Parse(oldobj, "z#", &oldbuf, &oldbuflen))
      return NULL;

    if (!PyArg_Parse(newobj, "z#", &newbuf, &newbuflen))
      return NULL;

    err = git_patch_from_buffers(&patch, oldbuf, oldbuflen, old_as_path,
                                 newbuf, newbuflen, new_as_path, &opts);
  }

  if (err < 0)
    return Error_set(err);

  return wrap_patch(patch, oldblob, newblob);
}

PyDoc_STRVAR(Patch_data__doc__, "The raw bytes of the patch's contents.");

PyObject *
Patch_data__get__(Patch *self)
{
    git_buf buf = {NULL};
    int err;
    PyObject *bytes;

    assert(self->patch);
    err = git_patch_to_buf(&buf, self->patch);
    if (err < 0)
        return Error_set(err);

    bytes = PyBytes_FromStringAndSize(buf.ptr, buf.size);
    git_buf_dispose(&buf);
    return bytes;
}

PyDoc_STRVAR(Patch_text__doc__,
    "Patch diff string. Can be None in some cases, such as empty commits.\n"
    "Note that this decodes the content to Unicode assuming UTF-8 encoding. "
    "For non-UTF-8 content that can lead be a lossy, non-reversible process. "
    "To access the raw, un-decoded patch, use `patch.data`.");

PyObject *
Patch_text__get__(Patch *self)
{
    git_buf buf = {NULL};
    int err;
    PyObject *text;

    assert(self->patch);
    err = git_patch_to_buf(&buf, self->patch);
    if (err < 0)
        return Error_set(err);

    text = to_unicode_n(buf.ptr, buf.size, NULL, NULL);
    git_buf_dispose(&buf);
    return text;
}

PyDoc_STRVAR(Patch_hunks__doc__, "hunks");

PyObject *
Patch_hunks__get__(Patch *self)
{
    size_t i, hunk_amounts;
    PyObject *py_hunks;
    PyObject *py_hunk;

    hunk_amounts = git_patch_num_hunks(self->patch);
    py_hunks = PyList_New(hunk_amounts);
    for (i = 0; i < hunk_amounts; i++) {
        py_hunk = wrap_diff_hunk(self, i);
        if (py_hunk == NULL)
            return NULL;

        PyList_SET_ITEM((PyObject*) py_hunks, i, py_hunk);
    }

    return py_hunks;
}


PyMethodDef Patch_methods[] = {
    {"create_from", (PyCFunction) Patch_create_from,
      METH_KEYWORDS | METH_VARARGS | METH_STATIC, Patch_create_from__doc__},
    {NULL}
};

PyGetSetDef Patch_getsetters[] = {
    GETTER(Patch, delta),
    GETTER(Patch, line_stats),
    GETTER(Patch, data),
    GETTER(Patch, text),
    GETTER(Patch, hunks),
    {NULL}
};

PyDoc_STRVAR(Patch__doc__, "Diff patch object.");

PyTypeObject PatchType = {
    PyVarObject_HEAD_INIT(NULL, 0)
    "_pygit2.Patch",                           /* tp_name           */
    sizeof(Patch),                             /* tp_basicsize      */
    0,                                         /* tp_itemsize       */
    (destructor)Patch_dealloc,                 /* tp_dealloc        */
    0,                                         /* tp_print          */
    0,                                         /* tp_getattr        */
    0,                                         /* tp_setattr        */
    0,                                         /* tp_compare        */
    0,                                         /* tp_repr           */
    0,                                         /* tp_as_number      */
    0,                                         /* tp_as_sequence    */
    0,                                         /* tp_as_mapping     */
    0,                                         /* tp_hash           */
    0,                                         /* tp_call           */
    0,                                         /* tp_str            */
    0,                                         /* tp_getattro       */
    0,                                         /* tp_setattro       */
    0,                                         /* tp_as_buffer      */
    Py_TPFLAGS_DEFAULT,                        /* tp_flags          */
    Patch__doc__,                              /* tp_doc            */
    0,                                         /* tp_traverse       */
    0,                                         /* tp_clear          */
    0,                                         /* tp_richcompare    */
    0,                                         /* tp_weaklistoffset */
    0,                                         /* tp_iter           */
    0,                                         /* tp_iternext       */
    Patch_methods,                             /* tp_methods        */
    0,                                         /* tp_members        */
    Patch_getsetters,                          /* tp_getset         */
    0,                                         /* tp_base           */
    0,                                         /* tp_dict           */
    0,                                         /* tp_descr_get      */
    0,                                         /* tp_descr_set      */
    0,                                         /* tp_dictoffset     */
    0,                                         /* tp_init           */
    0,                                         /* tp_alloc          */
    0,                                         /* tp_new            */
};
