// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (C) 2019 Daniel Borkmann <daniel@iogearbox.net> */

#include <stdio.h>
#include <string.h>
#include <libgen.h>

#include "l2md.h"

static int progress_sideband(const char *msg, int len, void *private_data)
{
	verbose("Remote: %.*s", len, msg);
	return 0;
}

static void progress_checkout(const char *path, size_t curr, size_t total,
			      void *private_data)
{
	verbose("Checkout: %zu/%zu\r", curr, total);
}

static void setup_fetch_opts(git_fetch_options *opts)
{
	opts->callbacks.sideband_progress = progress_sideband;
	opts->proxy_opts.type = GIT_PROXY_AUTO;
}

static void setup_checkout_opts(git_checkout_options *opts)
{
	opts->checkout_strategy = GIT_CHECKOUT_SAFE;
	opts->progress_cb = progress_checkout;
}

static void setup_clone_opts(git_clone_options *opts)
{
	setup_checkout_opts(&opts->checkout_opts);
	setup_fetch_opts(&opts->fetch_opts);
}

static void panic_git(const char *subject)
{
	const git_error *err = git_error_last();
	const char *err_str = err ? err->message : "unknown error";

	panic("%s: %s\n", subject, err_str);
}

static void warn_git(const char *subject)
{
	const git_error *err = git_error_last();
	const char *err_str = err ? err->message : "unknown error";

	warn("%s: %s\n", subject, err_str);
}

void repo_clone(struct config_repo *repo, struct config_url *url,
		const char *target)
{
	git_clone_options clone_opts = GIT_CLONE_OPTIONS_INIT;
	int ret;

	setup_clone_opts(&clone_opts);

	verbose("Cloning: %s\n", url->path);

	ret = git_clone(&repo->git, url->path, target, &clone_opts);
	if (ret)
		panic_git("Cannot clone git repo");

	git_repository_free(repo->git);
}

static int fetch_head(const char *ref_name, const char *remote_url,
		      const git_oid *oid, unsigned int merge,
		      void *private_data)
{
	char out[GIT_OID_HEXSZ + 1];

	if (merge) {
		verbose("Merging: %s commit %s\n", ref_name,
			git_oid_tostr(out, sizeof(out), oid));
		git_oid_cpy(private_data, oid);
	}

	return 0;
}

void repo_pull(struct config_repo *repo, struct config_url *url,
	       const char *target)
{
	git_checkout_options checkout_opts = GIT_CHECKOUT_OPTIONS_INIT;
	git_fetch_options fetch_opts = GIT_FETCH_OPTIONS_INIT;
	git_reference *head_cur, *head_new;
	git_annotated_commit *head;
	git_oid oid_to_merge;
	git_object *head_obj;
	git_remote *remote;
	int ret;

	ret = git_repository_open(&repo->git, target);
	if (ret)
		panic_git("Cannot open git repo");

	ret = git_remote_lookup(&remote, repo->git, "origin");
	if (ret)
		panic_git("Cannot look up origin");

	setup_fetch_opts(&fetch_opts);

	verbose("Fetching: %s\n", url->path);

	ret = git_remote_fetch(remote, NULL, &fetch_opts,
			       NULL);
	if (ret) {
		warn_git("Cannot fetch remote");
		goto out;
	}

	git_repository_fetchhead_foreach(repo->git, fetch_head,
					 &oid_to_merge);

	ret = git_annotated_commit_lookup(&head, repo->git,
					  &oid_to_merge);
	if (ret)
		panic_git("Cannot lookup head");

	ret = git_repository_head(&head_cur, repo->git);
	if (ret)
		panic_git("Cannot lookup current head");

	ret = git_object_lookup(&head_obj, repo->git, &oid_to_merge,
				GIT_OBJECT_COMMIT);
	if (ret)
		panic_git("Cannot lookup HEAD object");

	setup_checkout_opts(&checkout_opts);

	ret = git_checkout_tree(repo->git, head_obj, &checkout_opts);
	if (ret)
		panic_git("Cannot checkout tree");

	ret = git_reference_set_target(&head_new, head_cur, &oid_to_merge,
				       NULL);
	if (ret)
		panic_git("Cannot repoint HEAD");

	git_repository_state_cleanup(repo->git);

	git_annotated_commit_free(head);

	git_reference_free(head_cur);
	git_reference_free(head_new);

	git_object_free(head_obj);
out:
	git_remote_free(remote);
	git_repository_free(repo->git);
}

static void __repo_local_get(struct config *cfg, struct config_repo *repo,
			     struct config_url *url, const char *which,
			     char *out, size_t len)
{
	char tmp[PATH_MAX];

	strcpy(tmp, url->path);
	slprintf(out, len, "%s/%s/%s/%s", cfg->general.base, which,
		 repo->name, basename(tmp));
}

void repo_local_path(struct config *cfg, struct config_repo *repo,
		     struct config_url *url, char *out, size_t len)
{
	__repo_local_get(cfg, repo, url, REPOS, out, len);
}

void repo_local_oid(struct config *cfg, struct config_repo *repo,
		    struct config_url *url, char *out, size_t len)
{
	__repo_local_get(cfg, repo, url, OIDS, out, len);
}

void repo_walk_files(struct config *cfg, struct config_repo *repo, uint32_t url,
		     const char *path, const char *oid_last, char *oid_done,
		     void (*repo_walker)(struct config *cfg, struct config_repo *repo,
					 uint32_t url, const char *oid,
					 const void *raw, size_t len))
{
	char oid_curr[GIT_OID_HEXSZ + 1];
	struct timeval start, end, res;
	git_oid coid, loid, foid;
	bool have_first = false;
	const git_blob *blob;
	char spec[PATH_MAX];
	git_revwalk *walker;
	git_commit *commit;
	git_object *object;
	uint32_t count = 0;
	int ret, it;

	ret = git_repository_open(&repo->git, path);
	if (ret)
		panic_git("Cannot open git repo");

	ret = git_revwalk_new(&walker, repo->git);
	if (ret)
		panic_git("Cannot create ref walker");

	git_revwalk_sorting(walker, GIT_SORT_TIME);

	ret = git_revwalk_push_head(walker);
	if (ret)
		panic_git("Cannot push head onto ref walker");
	if (oid_last) {
		ret = git_oid_fromstrn(&loid, oid_last, GIT_OID_HEXSZ);
		if (ret)
			panic_git("Cannot convert to git oid");
	}

	gettimeofday(&start, NULL);

	while (!(it = git_revwalk_next(&coid, walker))) {
		ret = git_commit_lookup(&commit, repo->git, &coid);
		if (ret)
			panic_git("Cannot look up commit");

		if (!have_first) {
			git_oid_cpy(&foid, &coid);
			have_first = true;
		}

		if (oid_last && !git_oid_cmp(&loid, &coid)) {
			git_commit_free(commit);
			break;
		}

		if (!oid_last && repo->limit) {
			if (repo->initial_import == 0) {
				git_commit_free(commit);
				break;
			}
			repo->initial_import--;
		}

		git_oid_tostr(oid_curr, sizeof(oid_curr), &coid);
		slprintf(spec, sizeof(spec), "%s:%s", oid_curr, MAIL);

		ret = git_revparse_single(&object, repo->git, spec);
		if (ret == GIT_ENOTFOUND)
			goto skip;

		if (ret || git_object_type(object) != GIT_OBJECT_BLOB)
			panic_git("Cannot revparse object");

		blob = (const git_blob *)object;
		repo_walker(cfg, repo, url, oid_curr, git_blob_rawcontent(blob),
			    (size_t)git_blob_rawsize(blob));

		git_object_free(object);
		count++;
skip:
		git_commit_free(commit);
	}

	if (it && it != GIT_ITEROVER && !count)
		warn_git("Performing revwalk did not succeed! Repo might need repack");

	gettimeofday(&end, NULL);
	timeval_sub(&res, &end, &start);

	if (have_first)
		git_oid_tostr(oid_done, GIT_OID_HEXSZ + 1, &foid);
	if (have_first && count) {
		git_oid_tostr(oid_curr, sizeof(oid_curr), &loid);
		printf("Processed %u new mail(s) for %s. %s: %s -> %s in %ld.%02lds.\n",
		       count, repo->name, repo->urls[url].path, oid_last ? oid_curr :
		       "[none]", oid_done, res.tv_sec, (long)res.tv_usec);
	}

	git_revwalk_free(walker);
	git_repository_free(repo->git);
}