/***

  Oak - Non-Linear Video Editor
  Copyright (C) 2026 Oak Team

  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  This program 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.  If not, see <http://www.gnu.org/licenses/>.

***/

#ifndef OAKENGINE_PROJECT_H
#define OAKENGINE_PROJECT_H

#include "export.h"
#include "init.h"

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @file project.h
 * @brief C ABI for Oak project files (.ove)
 *
 * An OakEngineProject wraps the engine's olive::Project node graph. Projects
 * are created empty with oakengine_project_create() and must then be given
 * content exactly once: either oakengine_project_new() for a blank project or
 * oakengine_project_load() to read a project file (the engine's project
 * serializers require a fresh, uninitialized project, so loading into a
 * project that already has content is rejected with OAKENGINE_E_STATE).
 *
 * Sequences are owned by their project through Qt's QObject parent chain;
 * OakEngineSequence handles are borrowed views whose lifetime follows the
 * project. See timeline.h for the sequence function family.
 *
 * Conventions (matching oakengine/ipc.h):
 *   - Booleans are int (1/0).
 *   - Return codes: 0 (OAKENGINE_OK) on success, negative OAKENGINE_E_* on
 *     failure.
 *   - String output uses the buf/size convention: the return value is the
 *     number of characters that would have been written excluding the NUL,
 *     so buf == NULL or a short buffer queries the required size. The output
 *     is NUL-terminated whenever buf_size > 0. A negative return value is an
 *     OAKENGINE_E_* error code.
 *   - NULL handles are accepted everywhere and yield a no-op / zero result /
 *     OAKENGINE_E_INVALID.
 *
 * Undo/redo note: the engine's undo stack is a process-wide singleton held by
 * EngineCore (EngineCore::undo_stack()), not a per-project object. The
 * project_undo/project_redo family therefore operates on that global stack
 * and is not scoped to `self`; oakengine_project_new() and
 * oakengine_project_load() clear it, matching the application's
 * new/open-project behavior.
 */

/**
 * @brief Opaque project handle. Owned by the caller; release with
 * oakengine_project_free().
 */
typedef struct OakEngineProject OakEngineProject;

/**
 * @brief Opaque sequence (timeline) handle.
 *
 * Typedef'd here so project.h and timeline.h can be included in any order.
 * Handles are borrowed from their owning OakEngineProject (QObject parent
 * chain) and must NOT be freed; they become invalid when the project is
 * freed. The sequence function family lives in oakengine/timeline.h.
 */
typedef struct OakEngineSequence OakEngineSequence;

/**
 * @brief Allocate an empty project shell. Owned by the caller.
 *
 * The project has no content until exactly one of oakengine_project_new() or
 * oakengine_project_load() succeeds on it.
 */
OAKENGINE_API OakEngineProject *oakengine_project_create(void);

/**
 * @brief Destroy a project and everything it owns (including sequences).
 * NULL-safe.
 */
OAKENGINE_API void oakengine_project_free(OakEngineProject *self);

/**
 * @brief Initialize `self` as a new, blank project (untitled, not modified).
 *
 * Clears the global undo stack. Returns OAKENGINE_E_STATE if the project
 * already has content (new/load may only be applied once).
 */
OAKENGINE_API int oakengine_project_new(OakEngineProject *self);

/**
 * @brief Load project content from a .ove file.
 *
 * On success the project's filename is set to `path` and the modified flag is
 * cleared; the global undo stack is cleared. Footage is validated like the
 * engine does (EngineCore::validate_footage_in_loaded_project): files that
 * moved together with the project are resolved relatively; missing footage is
 * tolerated (no relink UI exists at this layer, so the project is accepted
 * as-is). On failure a human-readable reason is written to `err` using the
 * buf/size convention (err may be NULL) and a negative code is returned.
 */
OAKENGINE_API int oakengine_project_load(OakEngineProject *self,
										 const char *path, char *err,
										 int err_size);

/**
 * @brief Save the project to `path`.
 *
 * `path` == NULL saves under the project's current filename
 * (Project::filename()); saving an untitled project without a path fails with
 * OAKENGINE_E_INVALID. Files are gzip-compressed unless the target name ends
 * in ".ovexml" (mirrors the application behavior). On success the project's
 * filename is set to the target and the modified flag is cleared
 * (EngineCore::on_project_saved() semantics, minus the UI recent-list).
 */
OAKENGINE_API int oakengine_project_save(OakEngineProject *self,
										 const char *path);

OAKENGINE_API int oakengine_project_is_modified(const OakEngineProject *self);

/**
 * @brief Set the project modified flag (Project::set_modified).
 */
OAKENGINE_API int oakengine_project_set_modified(OakEngineProject *self,
												 int modified);

/**
 * @brief Project display name (Project::name(): the filename's base name, or
 * "(untitled)"). Uses the buf/size convention.
 */
OAKENGINE_API int oakengine_project_name(const OakEngineProject *self,
										 char *buf, int buf_size);

/**
 * @brief Full path the project was loaded from / saved to, or "" if untitled
 * (Project::filename()). Uses the buf/size convention.
 */
OAKENGINE_API int oakengine_project_filename(const OakEngineProject *self,
											 char *buf, int buf_size);

/**
 * @brief Number of footage items in the project.
 */
OAKENGINE_API int oakengine_project_footage_count(const OakEngineProject *self);

/**
 * @brief Stored filename of the footage item at `index` (Footage::filename(),
 * as recorded in the project file; may be relative). Uses the buf/size
 * convention; returns OAKENGINE_E_NOT_FOUND for an out-of-range index.
 */
OAKENGINE_API int oakengine_project_footage_filename(
	const OakEngineProject *self, int index, char *buf, int buf_size);

/**
 * @brief 1 if the footage file at `index` exists on disk, 0 if not.
 *
 * Mirrors the engine's validation rule: the stored path is checked as-is
 * first, then resolved relative to the project file's directory (footage
 * that moved together with the project stays online). Returns
 * OAKENGINE_E_NOT_FOUND for an out-of-range index.
 */
OAKENGINE_API int
oakengine_project_footage_is_online(const OakEngineProject *self, int index);

/* ---- Undo (global singleton stack, see the file comment above) ---------- */

OAKENGINE_API int oakengine_project_can_undo(const OakEngineProject *self);
OAKENGINE_API int oakengine_project_can_redo(const OakEngineProject *self);
OAKENGINE_API int oakengine_project_undo(OakEngineProject *self);
OAKENGINE_API int oakengine_project_redo(OakEngineProject *self);

/**
 * @brief Number of sequences (timelines) in the project.
 */
OAKENGINE_API int
oakengine_project_sequence_count(const OakEngineProject *self);

/**
 * @brief Borrowed handle of the sequence at `index`, or NULL when out of
 * range. Do NOT free; the sequence is owned by the project.
 */
OAKENGINE_API OakEngineSequence *
oakengine_project_sequence_at(const OakEngineProject *self, int index);

#ifdef __cplusplus
}
#endif

#endif /* OAKENGINE_PROJECT_H */