/*

 * Copyright (C) the libgit2 contributors. All rights reserved.

 *

 * This file is part of libgit2, distributed under the GNU GPL v2 with

 * a Linking Exception. For full terms see the included COPYING file.

 */

#include "common.h"

#include "vector.h"

#include "global.h"

#include "merge.h"

#include "merge_driver.h"

#include "git2/merge.h"

#include "git2/sys/merge.h"

static const char *merge_driver_name__text = "text";

static const char *merge_driver_name__union = "union";

static const char *merge_driver_name__binary = "binary";

struct merge_driver_registry {

	git_rwlock lock;

	git_vector drivers;

};

typedef struct {

	git_merge_driver *driver;

	int initialized;

	char name[GIT_FLEX_ARRAY];

} git_merge_driver_entry;

static struct merge_driver_registry merge_driver_registry;

static void git_merge_driver_global_shutdown(void);

const git_repository* git_merge_driver_source_repo(const git_merge_driver_source *src)

{

	assert(src);

	return src->repo;

}

const git_index_entry* git_merge_driver_source_ancestor(const git_merge_driver_source *src)

{

	assert(src);

	return src->ancestor;

}

const git_index_entry* git_merge_driver_source_ours(const git_merge_driver_source *src)

{

	assert(src);

	return src->ours;

}

const git_index_entry* git_merge_driver_source_theirs(const git_merge_driver_source *src)

{

	assert(src);

	return src->theirs;

}

const git_merge_file_options* git_merge_driver_source_file_options(const git_merge_driver_source *src)

{

	assert(src);

	return src->file_opts;

}

int git_merge_driver__builtin_apply(

	git_merge_driver *self,

	const char **path_out,

	uint32_t *mode_out,

	git_buf *merged_out,

	const char *filter_name,

	const git_merge_driver_source *src)

{

	git_merge_driver__builtin *driver = (git_merge_driver__builtin *)self;

	git_merge_file_options file_opts = GIT_MERGE_FILE_OPTIONS_INIT;

	git_merge_file_result result = {0};

	int error;

	GIT_UNUSED(filter_name);

	if (src->file_opts)

		memcpy(&file_opts, src->file_opts, sizeof(git_merge_file_options));

	if (driver->favor)

		file_opts.favor = driver->favor;

	if ((error = git_merge_file_from_index(&result, src->repo,

		src->ancestor, src->ours, src->theirs, &file_opts)) < 0)

		goto done;

	if (!result.automergeable &&

		!(file_opts.flags & GIT_MERGE_FILE_FAVOR__CONFLICTED)) {

		error = GIT_EMERGECONFLICT;

		goto done;

	}

	*path_out = git_merge_file__best_path(

		src->ancestor ? src->ancestor->path : NULL,

		src->ours ? src->ours->path : NULL,

		src->theirs ? src->theirs->path : NULL);

	*mode_out = git_merge_file__best_mode(

		src->ancestor ? src->ancestor->mode : 0,

		src->ours ? src->ours->mode : 0,

		src->theirs ? src->theirs->mode : 0);

	merged_out->ptr = (char *)result.ptr;

	merged_out->size = result.len;

	merged_out->asize = result.len;

	result.ptr = NULL;

done:

	git_merge_file_result_free(&result);

	return error;

}

static int merge_driver_binary_apply(

	git_merge_driver *self,

	const char **path_out,

	uint32_t *mode_out,

	git_buf *merged_out,

	const char *filter_name,

	const git_merge_driver_source *src)

{

	GIT_UNUSED(self);

	GIT_UNUSED(path_out);

	GIT_UNUSED(mode_out);

	GIT_UNUSED(merged_out);

	GIT_UNUSED(filter_name);

	GIT_UNUSED(src);

	return GIT_EMERGECONFLICT;

}

static int merge_driver_entry_cmp(const void *a, const void *b)

{

	const git_merge_driver_entry *entry_a = a;

	const git_merge_driver_entry *entry_b = b;

	return strcmp(entry_a->name, entry_b->name);

}

static int merge_driver_entry_search(const void *a, const void *b)

{

	const char *name_a = a;

	const git_merge_driver_entry *entry_b = b;

	return strcmp(name_a, entry_b->name);

}

git_merge_driver__builtin git_merge_driver__text = {

	{

		GIT_MERGE_DRIVER_VERSION,

		NULL,

		NULL,

		git_merge_driver__builtin_apply,

	},

	GIT_MERGE_FILE_FAVOR_NORMAL

};

git_merge_driver__builtin git_merge_driver__union = {

	{

		GIT_MERGE_DRIVER_VERSION,

		NULL,

		NULL,

		git_merge_driver__builtin_apply,

	},

	GIT_MERGE_FILE_FAVOR_UNION

};

git_merge_driver git_merge_driver__binary = {

	GIT_MERGE_DRIVER_VERSION,

	NULL,

	NULL,

	merge_driver_binary_apply

};

/* Note: callers must lock the registry before calling this function */

static int merge_driver_registry_insert(

	const char *name, git_merge_driver *driver)

{

	git_merge_driver_entry *entry;

	entry = git__calloc(1, sizeof(git_merge_driver_entry) + strlen(name) + 1);

	GITERR_CHECK_ALLOC(entry);

	strcpy(entry->name, name);

	entry->driver = driver;

	return git_vector_insert_sorted(

		&merge_driver_registry.drivers, entry, NULL);

}

int git_merge_driver_global_init(void)

{

	int error;

	if (git_rwlock_init(&merge_driver_registry.lock) < 0)

		return -1;

	if ((error = git_vector_init(&merge_driver_registry.drivers, 3,

		merge_driver_entry_cmp)) < 0)

		goto done;

	if ((error = merge_driver_registry_insert(

			merge_driver_name__text, &git_merge_driver__text.base)) < 0 ||

		(error = merge_driver_registry_insert(

			merge_driver_name__union, &git_merge_driver__union.base)) < 0 ||

		(error = merge_driver_registry_insert(

			merge_driver_name__binary, &git_merge_driver__binary)) < 0)

		goto done;

	git__on_shutdown(git_merge_driver_global_shutdown);

done:

	if (error < 0)

		git_vector_free_deep(&merge_driver_registry.drivers);

	return error;

}

static void git_merge_driver_global_shutdown(void)

{

	git_merge_driver_entry *entry;

	size_t i;

	if (git_rwlock_wrlock(&merge_driver_registry.lock) < 0)

		return;

	git_vector_foreach(&merge_driver_registry.drivers, i, entry) {

		if (entry->driver->shutdown)

			entry->driver->shutdown(entry->driver);

		git__free(entry);

	}

	git_vector_free(&merge_driver_registry.drivers);

	git_rwlock_wrunlock(&merge_driver_registry.lock);

	git_rwlock_free(&merge_driver_registry.lock);

}

/* Note: callers must lock the registry before calling this function */

static int merge_driver_registry_find(size_t *pos, const char *name)

{

	return git_vector_search2(pos, &merge_driver_registry.drivers,

		merge_driver_entry_search, name);

}

/* Note: callers must lock the registry before calling this function */

static git_merge_driver_entry *merge_driver_registry_lookup(

	size_t *pos, const char *name)

{

	git_merge_driver_entry *entry = NULL;

	if (!merge_driver_registry_find(pos, name))

		entry = git_vector_get(&merge_driver_registry.drivers, *pos);

	return entry;

}

int git_merge_driver_register(const char *name, git_merge_driver *driver)

{

	int error;

	assert(name && driver);

	if (git_rwlock_wrlock(&merge_driver_registry.lock) < 0) {

		giterr_set(GITERR_OS, "failed to lock merge driver registry");

		return -1;

	}

	if (!merge_driver_registry_find(NULL, name)) {

		giterr_set(GITERR_MERGE, "attempt to reregister existing driver '%s'",

			name);

		error = GIT_EEXISTS;

		goto done;

	}

	error = merge_driver_registry_insert(name, driver);

done:

	git_rwlock_wrunlock(&merge_driver_registry.lock);

	return error;

}

int git_merge_driver_unregister(const char *name)

{

	git_merge_driver_entry *entry;

	size_t pos;

	int error = 0;

	if (git_rwlock_wrlock(&merge_driver_registry.lock) < 0) {

		giterr_set(GITERR_OS, "failed to lock merge driver registry");

		return -1;

	}

	if ((entry = merge_driver_registry_lookup(&pos, name)) == NULL) {

		giterr_set(GITERR_MERGE, "cannot find merge driver '%s' to unregister",

			name);

		error = GIT_ENOTFOUND;

		goto done;

	}

	git_vector_remove(&merge_driver_registry.drivers, pos);

	if (entry->initialized && entry->driver->shutdown) {

		entry->driver->shutdown(entry->driver);

		entry->initialized = false;

	}

	git__free(entry);

done:

	git_rwlock_wrunlock(&merge_driver_registry.lock);

	return error;

}

git_merge_driver *git_merge_driver_lookup(const char *name)

{

	git_merge_driver_entry *entry;

	size_t pos;

	int error;

	/* If we've decided the merge driver to use internally - and not

	 * based on user configuration (in merge_driver_name_for_path)

	 * then we can use a hardcoded name to compare instead of bothering

	 * to take a lock and look it up in the vector.

	 */

	if (name == merge_driver_name__text)

		return &git_merge_driver__text.base;

	else if (name == merge_driver_name__binary)

		return &git_merge_driver__binary;

	if (git_rwlock_rdlock(&merge_driver_registry.lock) < 0) {

		giterr_set(GITERR_OS, "failed to lock merge driver registry");

		return NULL;

	}

	entry = merge_driver_registry_lookup(&pos, name);

	git_rwlock_rdunlock(&merge_driver_registry.lock);

	if (entry == NULL) {

		giterr_set(GITERR_MERGE, "cannot use an unregistered filter");

		return NULL;

	}

	if (!entry->initialized) {

		if (entry->driver->initialize &&

			(error = entry->driver->initialize(entry->driver)) < 0)

			return NULL;

		entry->initialized = 1;

	}

	return entry->driver;

}

static int merge_driver_name_for_path(

	const char **out,

	git_repository *repo,

	const char *path,

	const char *default_driver)

{

	const char *value;

	int error;

	*out = NULL;

	if ((error = git_attr_get(&value, repo, 0, path, "merge")) < 0)

		return error;

	/* set: use the built-in 3-way merge driver ("text") */

	if (GIT_ATTR_TRUE(value))

		*out = merge_driver_name__text;

	/* unset: do not merge ("binary") */

	else if (GIT_ATTR_FALSE(value))

		*out = merge_driver_name__binary;

	else if (GIT_ATTR_UNSPECIFIED(value) && default_driver)

		*out = default_driver;

	else if (GIT_ATTR_UNSPECIFIED(value))

		*out = merge_driver_name__text;

	else

		*out = value;

	return 0;

}

GIT_INLINE(git_merge_driver *) merge_driver_lookup_with_wildcard(

	const char *name)

{

	git_merge_driver *driver = git_merge_driver_lookup(name);

	if (driver == NULL)

		driver = git_merge_driver_lookup("*");

	return driver;

}

int git_merge_driver_for_source(

	const char **name_out,

	git_merge_driver **driver_out,

	const git_merge_driver_source *src)

{

	const char *path, *driver_name;

	int error = 0;

	path = git_merge_file__best_path(

		src->ancestor ? src->ancestor->path : NULL,

		src->ours ? src->ours->path : NULL,

		src->theirs ? src->theirs->path : NULL);

	if ((error = merge_driver_name_for_path(

			&driver_name, src->repo, path, src->default_driver)) < 0)

		return error;

	*name_out = driver_name;

	*driver_out = merge_driver_lookup_with_wildcard(driver_name);

	return error;

}