/*

 * libgit2 "general" example - shows basic libgit2 concepts

 *

 * Written by the libgit2 contributors

 *

 * To the extent possible under law, the author(s) have dedicated all copyright

 * and related and neighboring rights to this software to the public domain

 * worldwide. This software is distributed without any warranty.

 *

 * You should have received a copy of the CC0 Public Domain Dedication along

 * with this software. If not, see

 * <http://creativecommons.org/publicdomain/zero/1.0/>.

 */

/**

 * [**libgit2**][lg] is a portable, pure C implementation of the Git core

 * methods provided as a re-entrant linkable library with a solid API,

 * allowing you to write native speed custom Git applications in any

 * language which supports C bindings.

 *

 * This file is an example of using that API in a real, compilable C file.

 * As the API is updated, this file will be updated to demonstrate the new

 * functionality.

 *

 * If you're trying to write something in C using [libgit2][lg], you should

 * also check out the generated [API documentation][ap]. We try to link to

 * the relevant sections of the API docs in each section in this file.

 *

 * **libgit2** (for the most part) only implements the core plumbing

 * functions, not really the higher level porcelain stuff. For a primer on

 * Git Internals that you will need to know to work with Git at this level,

 * check out [Chapter 10][pg] of the Pro Git book.

 *

 * [lg]: http://libgit2.github.com

 * [ap]: http://libgit2.github.com/libgit2

 * [pg]: https://git-scm.com/book/en/v2/Git-Internals-Plumbing-and-Porcelain

 */

/**

 * ### Includes

 *

 * Including the `git2.h` header will include all the other libgit2 headers

 * that you need.  It should be the only thing you need to include in order

 * to compile properly and get all the libgit2 API.

 */

#include <git2.h>

#include <stdio.h>

#include <string.h>

static void oid_parsing(git_oid *out);

static void object_database(git_repository *repo, git_oid *oid);

static void commit_writing(git_repository *repo);

static void commit_parsing(git_repository *repo);

static void tag_parsing(git_repository *repo);

static void tree_parsing(git_repository *repo);

static void blob_parsing(git_repository *repo);

static void revwalking(git_repository *repo);

static void index_walking(git_repository *repo);

static void reference_listing(git_repository *repo);

static void config_files(const char *repo_path, git_repository *repo);

/**

 * Almost all libgit2 functions return 0 on success or negative on error.

 * This is not production quality error checking, but should be sufficient

 * as an example.

 */

static void check_error(int error_code, const char *action)

{

	const git_error *error = giterr_last();

	if (!error_code)

		return;

	printf("Error %d %s - %s\n", error_code, action,

			(error && error->message) ? error->message : "???");

	exit(1);

}

int main (int argc, char** argv)

{

	int error;

	git_oid oid;

	char *repo_path;

	git_repository *repo;

	/**

	 * Initialize the library, this will set up any global state which libgit2 needs

	 * including threading and crypto

	 */

	git_libgit2_init();

	/**

	 * ### Opening the Repository

	 *

	 * There are a couple of methods for opening a repository, this being the

	 * simplest.  There are also [methods][me] for specifying the index file

	 * and work tree locations, here we assume they are in the normal places.

	 *

	 * (Try running this program against tests/resources/testrepo.git.)

	 *

	 * [me]: http://libgit2.github.com/libgit2/#HEAD/group/repository

	 */

	repo_path = (argc > 1) ? argv[1] : "/opt/libgit2-test/.git";

	error = git_repository_open(&repo, repo_path);

	check_error(error, "opening repository");

	oid_parsing(&oid;;

	object_database(repo, &oid;;

	commit_writing(repo);

	commit_parsing(repo);

	tag_parsing(repo);

	tree_parsing(repo);

	blob_parsing(repo);

	revwalking(repo);

	index_walking(repo);

	reference_listing(repo);

	config_files(repo_path, repo);

	/**

	 * Finally, when you're done with the repository, you can free it as well.

	 */

	git_repository_free(repo);

	return 0;

}

/**

 * ### SHA-1 Value Conversions

 */

static void oid_parsing(git_oid *oid)

{

	char out[GIT_OID_HEXSZ+1];

	char hex[] = "4a202b346bb0fb0db7eff3cffeb3c70babbd2045";

	printf("*Hex to Raw*\n");

	/**

	 * For our first example, we will convert a 40 character hex value to the

	 * 20 byte raw SHA1 value.

	 *

	 * The `git_oid` is the structure that keeps the SHA value. We will use

	 * this throughout the example for storing the value of the current SHA

	 * key we're working with.

	 */

	git_oid_fromstr(oid, hex);

	// Once we've converted the string into the oid value, we can get the raw

	// value of the SHA by accessing `oid.id`

	// Next we will convert the 20 byte raw SHA1 value to a human readable 40

	// char hex value.

	printf("\n*Raw to Hex*\n");

	out[GIT_OID_HEXSZ] = '\0';

	/**

	 * If you have a oid, you can easily get the hex value of the SHA as well.

	 */

	git_oid_fmt(out, oid);

	/**

	 * If you have a oid, you can easily get the hex value of the SHA as well.

	 */

	git_oid_fmt(out, oid);

	printf("SHA hex string: %s\n", out);

}

/**

 * ### Working with the Object Database

 *

 * **libgit2** provides [direct access][odb] to the object database.  The

 * object database is where the actual objects are stored in Git. For

 * working with raw objects, we'll need to get this structure from the

 * repository.

 *

 * [odb]: http://libgit2.github.com/libgit2/#HEAD/group/odb

 */

static void object_database(git_repository *repo, git_oid *oid)

{

	char oid_hex[GIT_OID_HEXSZ+1] = { 0 };

	const unsigned char *data;

	const char *str_type;

	int error;

	git_odb_object *obj;

	git_odb *odb;

	git_otype otype;

	git_repository_odb(&odb, repo);

	/**

	 * #### Raw Object Reading

	 */

	printf("\n*Raw Object Read*\n");

	/**

	 * We can read raw objects directly from the object database if we have

	 * the oid (SHA) of the object.  This allows us to access objects without

	 * knowing their type and inspect the raw bytes unparsed.

	 */

	error = git_odb_read(&obj, odb, oid);

	check_error(error, "finding object in repository");

	/**

	 * A raw object only has three properties - the type (commit, blob, tree

	 * or tag), the size of the raw data and the raw, unparsed data itself.

	 * For a commit or tag, that raw data is human readable plain ASCII

	 * text. For a blob it is just file contents, so it could be text or

	 * binary data. For a tree it is a special binary format, so it's unlikely

	 * to be hugely helpful as a raw object.

	 */

	data = (const unsigned char *)git_odb_object_data(obj);

	otype = git_odb_object_type(obj);

	/**

	 * We provide methods to convert from the object type which is an enum, to

	 * a string representation of that value (and vice-versa).

	 */

	str_type = git_object_type2string(otype);

	printf("object length and type: %d, %s\nobject data: %s\n",

			(int)git_odb_object_size(obj),

			str_type, data);

	/**

	 * For proper memory management, close the object when you are done with

	 * it or it will leak memory.

	 */

	git_odb_object_free(obj);

	/**

	 * #### Raw Object Writing

	 */

	printf("\n*Raw Object Write*\n");

	/**

	 * You can also write raw object data to Git. This is pretty cool because

	 * it gives you direct access to the key/value properties of Git.  Here

	 * we'll write a new blob object that just contains a simple string.

	 * Notice that we have to specify the object type as the `git_otype` enum.

	 */

	git_odb_write(oid, odb, "test data", sizeof("test data") - 1, GIT_OBJ_BLOB);

	/**

	 * Now that we've written the object, we can check out what SHA1 was

	 * generated when the object was written to our database.

	 */

	git_oid_fmt(oid_hex, oid);

	printf("Written Object: %s\n", oid_hex);

	/**

	 * Free the object database after usage.

	 */

	git_odb_free(odb);

}

/**

 * #### Writing Commits

 *

 * libgit2 provides a couple of methods to create commit objects easily as

 * well. There are four different create signatures, we'll just show one

 * of them here.  You can read about the other ones in the [commit API

 * docs][cd].

 *

 * [cd]: http://libgit2.github.com/libgit2/#HEAD/group/commit

 */

static void commit_writing(git_repository *repo)

{

	git_oid tree_id, parent_id, commit_id;

	git_tree *tree;

	git_commit *parent;

	git_signature *author, *committer;

	char oid_hex[GIT_OID_HEXSZ+1] = { 0 };

	printf("\n*Commit Writing*\n");

	/**

	 * Creating signatures for an authoring identity and time is simple.  You

	 * will need to do this to specify who created a commit and when.  Default

	 * values for the name and email should be found in the `user.name` and

	 * `user.email` configuration options.  See the `config` section of this

	 * example file to see how to access config values.

	 */

	git_signature_new(&author,

			"Scott Chacon", "schacon@gmail.com", 123456789, 60);

	git_signature_new(&committer,

			"Scott A Chacon", "scott@github.com", 987654321, 90);

	/**

	 * Commit objects need a tree to point to and optionally one or more

	 * parents.  Here we're creating oid objects to create the commit with,

	 * but you can also use

	 */

	git_oid_fromstr(&tree_id, "f60079018b664e4e79329a7ef9559c8d9e0378d1");

	git_tree_lookup(&tree, repo, &tree_id);

	git_oid_fromstr(&parent_id, "5b5b025afb0b4c913b4c338a42934a3863bf3644");

	git_commit_lookup(&parent, repo, &parent_id);

	/**

	 * Here we actually create the commit object with a single call with all

	 * the values we need to create the commit.  The SHA key is written to the

	 * `commit_id` variable here.

	 */

	git_commit_create_v(

			&commit_id, /* out id */

			repo,

			NULL, /* do not update the HEAD */

			author,

			committer,

			NULL, /* use default message encoding */

			"example commit",

			tree,

			1, parent);

	/**

	 * Now we can take a look at the commit SHA we've generated.

	 */

	git_oid_fmt(oid_hex, &commit_id);

	printf("New Commit: %s\n", oid_hex);

	/**

	 * Free all objects used in the meanwhile.

	 */

	git_tree_free(tree);

	git_commit_free(parent);

	git_signature_free(author);

	git_signature_free(committer);

}

/**

 * ### Object Parsing

 *

 * libgit2 has methods to parse every object type in Git so you don't have

 * to work directly with the raw data. This is much faster and simpler

 * than trying to deal with the raw data yourself.

 */

/**

 * #### Commit Parsing

 *

 * [Parsing commit objects][pco] is simple and gives you access to all the

 * data in the commit - the author (name, email, datetime), committer

 * (same), tree, message, encoding and parent(s).

 *

 * [pco]: http://libgit2.github.com/libgit2/#HEAD/group/commit

 */

static void commit_parsing(git_repository *repo)

{

	const git_signature *author, *cmtter;

	git_commit *commit, *parent;

	git_oid oid;

	char oid_hex[GIT_OID_HEXSZ+1];

	const char *message;

	unsigned int parents, p;

	int error;

	time_t time;

	printf("\n*Commit Parsing*\n");

	git_oid_fromstr(&oid, "8496071c1b46c854b31185ea97743be6a8774479");

	error = git_commit_lookup(&commit, repo, &oid;;

	check_error(error, "looking up commit");

	/**

	 * Each of the properties of the commit object are accessible via methods,

	 * including commonly needed variations, such as `git_commit_time` which

	 * returns the author time and `git_commit_message` which gives you the

	 * commit message (as a NUL-terminated string).

	 */

	message  = git_commit_message(commit);

	author   = git_commit_author(commit);

	cmtter   = git_commit_committer(commit);

	time    = git_commit_time(commit);

	/**

	 * The author and committer methods return [git_signature] structures,

	 * which give you name, email and `when`, which is a `git_time` structure,

	 * giving you a timestamp and timezone offset.

	 */

	printf("Author: %s (%s)\nCommitter: %s (%s)\nDate: %s\nMessage: %s\n",

		author->name, author->email,

		cmtter->name, cmtter->email,

		ctime(&time), message);

	/**

	 * Commits can have zero or more parents. The first (root) commit will

	 * have no parents, most commits will have one (i.e. the commit it was

	 * based on) and merge commits will have two or more.  Commits can

	 * technically have any number, though it's rare to have more than two.

	 */

	parents  = git_commit_parentcount(commit);

	for (p = 0;p < parents;p++) {

		memset(oid_hex, 0, sizeof(oid_hex));

		git_commit_parent(&parent, commit, p);

		git_oid_fmt(oid_hex, git_commit_id(parent));

		printf("Parent: %s\n", oid_hex);

		git_commit_free(parent);

	}

	git_commit_free(commit);

}

/**

 * #### Tag Parsing

 *

 * You can parse and create tags with the [tag management API][tm], which

 * functions very similarly to the commit lookup, parsing and creation

 * methods, since the objects themselves are very similar.

 *

 * [tm]: http://libgit2.github.com/libgit2/#HEAD/group/tag

 */

static void tag_parsing(git_repository *repo)

{

	git_commit *commit;

	git_otype type;

	git_tag *tag;

	git_oid oid;

	const char *name, *message;

	int error;

	printf("\n*Tag Parsing*\n");

	/**

	 * We create an oid for the tag object if we know the SHA and look it up

	 * the same way that we would a commit (or any other object).

	 */

	git_oid_fromstr(&oid, "b25fa35b38051e4ae45d4222e795f9df2e43f1d1");

	error = git_tag_lookup(&tag, repo, &oid;;

	check_error(error, "looking up tag");

	/**

	 * Now that we have the tag object, we can extract the information it

	 * generally contains: the target (usually a commit object), the type of

	 * the target object (usually 'commit'), the name ('v1.0'), the tagger (a

	 * git_signature - name, email, timestamp), and the tag message.

	 */

	git_tag_target((git_object **)&commit, tag);

	name = git_tag_name(tag);		/* "test" */

	type = git_tag_target_type(tag);	/* GIT_OBJ_COMMIT (otype enum) */

	message = git_tag_message(tag);		/* "tag message\n" */

	printf("Tag Name: %s\nTag Type: %s\nTag Message: %s\n",

		name, git_object_type2string(type), message);

	/**

	 * Free both the commit and tag after usage.

	 */

	git_commit_free(commit);

	git_tag_free(tag);

}

/**

 * #### Tree Parsing

 *

 * [Tree parsing][tp] is a bit different than the other objects, in that

 * we have a subtype which is the tree entry.  This is not an actual

 * object type in Git, but a useful structure for parsing and traversing

 * tree entries.

 *

 * [tp]: http://libgit2.github.com/libgit2/#HEAD/group/tree

 */

static void tree_parsing(git_repository *repo)

{

	const git_tree_entry *entry;

	size_t cnt;

	git_object *obj;

	git_tree *tree;

	git_oid oid;

	printf("\n*Tree Parsing*\n");

	/**

	 * Create the oid and lookup the tree object just like the other objects.

	 */

	git_oid_fromstr(&oid, "f60079018b664e4e79329a7ef9559c8d9e0378d1");

	git_tree_lookup(&tree, repo, &oid;;

	/**

	 * Getting the count of entries in the tree so you can iterate over them

	 * if you want to.

	 */

	cnt = git_tree_entrycount(tree); /* 2 */

	printf("tree entries: %d\n", (int) cnt);

	entry = git_tree_entry_byindex(tree, 0);

	printf("Entry name: %s\n", git_tree_entry_name(entry)); /* "README" */

	/**

	 * You can also access tree entries by name if you know the name of the

	 * entry you're looking for.

	 */

	entry = git_tree_entry_byname(tree, "README");

	git_tree_entry_name(entry); /* "README" */

	/**

	 * Once you have the entry object, you can access the content or subtree

	 * (or commit, in the case of submodules) that it points to.  You can also

	 * get the mode if you want.

	 */

	git_tree_entry_to_object(&obj, repo, entry); /* blob */

	/**

	 * Remember to close the looked-up object and tree once you are done using it

	 */

	git_object_free(obj);

	git_tree_free(tree);

}

/**

 * #### Blob Parsing

 *

 * The last object type is the simplest and requires the least parsing

 * help. Blobs are just file contents and can contain anything, there is

 * no structure to it. The main advantage to using the [simple blob

 * api][ba] is that when you're creating blobs you don't have to calculate

 * the size of the content.  There is also a helper for reading a file

 * from disk and writing it to the db and getting the oid back so you

 * don't have to do all those steps yourself.

 *

 * [ba]: http://libgit2.github.com/libgit2/#HEAD/group/blob

 */

static void blob_parsing(git_repository *repo)

{

	git_blob *blob;

	git_oid oid;

	printf("\n*Blob Parsing*\n");

	git_oid_fromstr(&oid, "1385f264afb75a56a5bec74243be9b367ba4ca08");

	git_blob_lookup(&blob, repo, &oid;;

	/**

	 * You can access a buffer with the raw contents of the blob directly.

	 * Note that this buffer may not be contain ASCII data for certain blobs

	 * (e.g. binary files): do not consider the buffer a NULL-terminated

	 * string, and use the `git_blob_rawsize` attribute to find out its exact

	 * size in bytes

	 * */

	printf("Blob Size: %ld\n", (long)git_blob_rawsize(blob)); /* 8 */

	git_blob_rawcontent(blob); /* "content" */

	/**

	 * Free the blob after usage.

	 */

	git_blob_free(blob);

}

/**

 * ### Revwalking

 *

 * The libgit2 [revision walking api][rw] provides methods to traverse the

 * directed graph created by the parent pointers of the commit objects.

 * Since all commits point back to the commit that came directly before

 * them, you can walk this parentage as a graph and find all the commits

 * that were ancestors of (reachable from) a given starting point.  This

 * can allow you to create `git log` type functionality.

 *

 * [rw]: http://libgit2.github.com/libgit2/#HEAD/group/revwalk

 */

static void revwalking(git_repository *repo)

{

	const git_signature *cauth;

	const char *cmsg;

	int error;

	git_revwalk *walk;

	git_commit *wcommit;

	git_oid oid;

	printf("\n*Revwalking*\n");

	git_oid_fromstr(&oid, "5b5b025afb0b4c913b4c338a42934a3863bf3644");

	/**

	 * To use the revwalker, create a new walker, tell it how you want to sort

	 * the output and then push one or more starting points onto the walker.

	 * If you want to emulate the output of `git log` you would push the SHA

	 * of the commit that HEAD points to into the walker and then start

	 * traversing them.  You can also 'hide' commits that you want to stop at

	 * or not see any of their ancestors.  So if you want to emulate `git log

	 * branch1..branch2`, you would push the oid of `branch2` and hide the oid

	 * of `branch1`.

	 */

	git_revwalk_new(&walk, repo);

	git_revwalk_sorting(walk, GIT_SORT_TOPOLOGICAL | GIT_SORT_REVERSE);

	git_revwalk_push(walk, &oid;;

	/**

	 * Now that we have the starting point pushed onto the walker, we start

	 * asking for ancestors. It will return them in the sorting order we asked

	 * for as commit oids.  We can then lookup and parse the committed pointed

	 * at by the returned OID; note that this operation is specially fast

	 * since the raw contents of the commit object will be cached in memory

	 */

	while ((git_revwalk_next(&oid, walk)) == 0) {

		error = git_commit_lookup(&wcommit, repo, &oid;;

		check_error(error, "looking up commit during revwalk");

		cmsg  = git_commit_message(wcommit);

		cauth = git_commit_author(wcommit);

		printf("%s (%s)\n", cmsg, cauth->email);

		git_commit_free(wcommit);

	}

	/**

	 * Like the other objects, be sure to free the revwalker when you're done

	 * to prevent memory leaks.  Also, make sure that the repository being

	 * walked it not deallocated while the walk is in progress, or it will

	 * result in undefined behavior

	 */

	git_revwalk_free(walk);

}

/**

 * ### Index File Manipulation *

 * The [index file API][gi] allows you to read, traverse, update and write

 * the Git index file (sometimes thought of as the staging area).

 *

 * [gi]: http://libgit2.github.com/libgit2/#HEAD/group/index

 */

static void index_walking(git_repository *repo)

{

	git_index *index;

	unsigned int i, ecount;

	printf("\n*Index Walking*\n");

	/**

	 * You can either open the index from the standard location in an open

	 * repository, as we're doing here, or you can open and manipulate any

	 * index file with `git_index_open_bare()`. The index for the repository

	 * will be located and loaded from disk.

	 */

	git_repository_index(&index, repo);

	/**

	 * For each entry in the index, you can get a bunch of information

	 * including the SHA (oid), path and mode which map to the tree objects

	 * that are written out.  It also has filesystem properties to help

	 * determine what to inspect for changes (ctime, mtime, dev, ino, uid,

	 * gid, file_size and flags) All these properties are exported publicly in

	 * the `git_index_entry` struct

	 */

	ecount = git_index_entrycount(index);

	for (i = 0; i < ecount; ++i) {

		const git_index_entry *e = git_index_get_byindex(index, i);

		printf("path: %s\n", e->path);

		printf("mtime: %d\n", (int)e->mtime.seconds);

		printf("fs: %d\n", (int)e->file_size);

	}

	git_index_free(index);

}

/**

 * ### References

 *

 * The [reference API][ref] allows you to list, resolve, create and update

 * references such as branches, tags and remote references (everything in

 * the .git/refs directory).

 *

 * [ref]: http://libgit2.github.com/libgit2/#HEAD/group/reference

 */

static void reference_listing(git_repository *repo)

{

	git_strarray ref_list;

	unsigned i;

	printf("\n*Reference Listing*\n");

	/**

	 * Here we will implement something like `git for-each-ref` simply listing

	 * out all available references and the object SHA they resolve to.

	 *

	 * Now that we have the list of reference names, we can lookup each ref

	 * one at a time and resolve them to the SHA, then print both values out.

	 */

	git_reference_list(&ref_list, repo);

	for (i = 0; i < ref_list.count; ++i) {

		git_reference *ref;

		char oid_hex[GIT_OID_HEXSZ+1] = GIT_OID_HEX_ZERO;

		const char *refname;

		refname = ref_list.strings[i];

		git_reference_lookup(&ref, repo, refname);

		switch (git_reference_type(ref)) {

			case GIT_REF_OID:

				git_oid_fmt(oid_hex, git_reference_target(ref));

				printf("%s [%s]\n", refname, oid_hex);

				break;

			case GIT_REF_SYMBOLIC:

				printf("%s => %s\n", refname, git_reference_symbolic_target(ref));

				break;

			default:

				fprintf(stderr, "Unexpected reference type\n");

				exit(1);

		}

		git_reference_free(ref);

	}

	git_strarray_free(&ref_list);

}

/**

 * ### Config Files

 *

 * The [config API][config] allows you to list and updatee config values

 * in any of the accessible config file locations (system, global, local).

 *

 * [config]: http://libgit2.github.com/libgit2/#HEAD/group/config

 */

static void config_files(const char *repo_path, git_repository* repo)

{

	const char *email;

	char config_path[256];

	int32_t autocorrect;

	git_config *cfg;

	git_config *snap_cfg;

	printf("\n*Config Listing*\n");

	/**

	 * Open a config object so we can read global values from it.

	 */

	sprintf(config_path, "%s/config", repo_path);

	check_error(git_config_open_ondisk(&cfg, config_path), "opening config");

	if (git_config_get_int32(&autocorrect, cfg, "help.autocorrect") == 0)

		printf("Autocorrect: %d\n", autocorrect);

	check_error(git_repository_config_snapshot(&snap_cfg, repo), "config snapshot");

	git_config_get_string(&email, snap_cfg, "user.email");

	printf("Email: %s\n", email);

	/**

	 * Remember to free the configurations after usage.

	 */

	git_config_free(cfg);

	git_config_free(snap_cfg);

}