#include "cache.h"
#include "config.h"
#include "refs.h"
#include "builtin.h"
#include "parse-options.h"
#include "quote.h"
#include "argv-array.h"

static const char * const git_update_ref_usage[] = {
        N_("git update-ref [<options>] -d <refname> [<old-val>]"),
        N_("git update-ref [<options>]    <refname> <new-val> [<old-val>]"),
        N_("git update-ref [<options>] --stdin [-z]"),
        NULL
};

static char line_termination = '\n';
static unsigned int update_flags;
static unsigned int default_flags;
static unsigned create_reflog_flag;
static const char *msg;

/*
 * Parse one whitespace- or NUL-terminated, possibly C-quoted argument
 * and append the result to arg.  Return a pointer to the terminator.
 * Die if there is an error in how the argument is C-quoted.  This
 * function is only used if not -z.
 */
static const char *parse_arg(const char *next, struct strbuf *arg)
{
        if (*next == '"') {
                const char *orig = next;

                if (unquote_c_style(arg, next, &next))
                        die("badly quoted argument: %s", orig);
                if (*next && !isspace(*next))
                        die("unexpected character after quoted argument: %s", orig);
        } else {
                while (*next && !isspace(*next))
                        strbuf_addch(arg, *next++);
        }

        return next;
}

/*
 * Parse the reference name immediately after "command SP".  If not
 * -z, then handle C-quoting.  Return a pointer to a newly allocated
 * string containing the name of the reference, or NULL if there was
 * an error.  Update *next to point at the character that terminates
 * the argument.  Die if C-quoting is malformed or the reference name
 * is invalid.
 */
static char *parse_refname(struct strbuf *input, const char **next)
{
        struct strbuf ref = STRBUF_INIT;

        if (line_termination) {
                /* Without -z, use the next argument */
                *next = parse_arg(*next, &ref);
        } else {
                /* With -z, use everything up to the next NUL */
                strbuf_addstr(&ref, *next);
                *next += ref.len;
        }

        if (!ref.len) {
                strbuf_release(&ref);
                return NULL;
        }

        if (check_refname_format(ref.buf, REFNAME_ALLOW_ONELEVEL))
                die("invalid ref format: %s", ref.buf);

        return strbuf_detach(&ref, NULL);
}

/*
 * The value being parsed is <oldvalue> (as opposed to <newvalue>; the
 * difference affects which error messages are generated):
 */
#define PARSE_SHA1_OLD 0x01

/*
 * For backwards compatibility, accept an empty string for update's
 * <newvalue> in binary mode to be equivalent to specifying zeros.
 */
#define PARSE_SHA1_ALLOW_EMPTY 0x02

/*
 * Parse an argument separator followed by the next argument, if any.
 * If there is an argument, convert it to a SHA-1, write it to sha1,
 * set *next to point at the character terminating the argument, and
 * return 0.  If there is no argument at all (not even the empty
 * string), return 1 and leave *next unchanged.  If the value is
 * provided but cannot be converted to a SHA-1, die.  flags can
 * include PARSE_SHA1_OLD and/or PARSE_SHA1_ALLOW_EMPTY.
 */
static int parse_next_oid(struct strbuf *input, const char **next,
                          struct object_id *oid,
                          const char *command, const char *refname,
                          int flags)
{
        struct strbuf arg = STRBUF_INIT;
        int ret = 0;

        if (*next == input->buf + input->len)
                goto eof;

        if (line_termination) {
                /* Without -z, consume SP and use next argument */
                if (!**next || **next == line_termination)
                        return 1;
                if (**next != ' ')
                        die("%s %s: expected SP but got: %s",
                            command, refname, *next);
                (*next)++;
                *next = parse_arg(*next, &arg);
                if (arg.len) {
                        if (get_oid(arg.buf, oid))
                                goto invalid;
                } else {
                        /* Without -z, an empty value means all zeros: */
                        oidclr(oid);
                }
        } else {
                /* With -z, read the next NUL-terminated line */
                if (**next)
                        die("%s %s: expected NUL but got: %s",
                            command, refname, *next);
                (*next)++;
                if (*next == input->buf + input->len)
                        goto eof;
                strbuf_addstr(&arg, *next);
                *next += arg.len;

                if (arg.len) {
                        if (get_oid(arg.buf, oid))
                                goto invalid;
                } else if (flags & PARSE_SHA1_ALLOW_EMPTY) {
                        /* With -z, treat an empty value as all zeros: */
                        warning("%s %s: missing <newvalue>, treating as zero",
                                command, refname);
                        oidclr(oid);
                } else {
                        /*
                         * With -z, an empty non-required value means
                         * unspecified:
                         */
                        ret = 1;
                }
        }

        strbuf_release(&arg);

        return ret;

 invalid:
        die(flags & PARSE_SHA1_OLD ?
            "%s %s: invalid <oldvalue>: %s" :
            "%s %s: invalid <newvalue>: %s",
            command, refname, arg.buf);

 eof:
        die(flags & PARSE_SHA1_OLD ?
            "%s %s: unexpected end of input when reading <oldvalue>" :
            "%s %s: unexpected end of input when reading <newvalue>",
            command, refname);
}


/*
 * The following five parse_cmd_*() functions parse the corresponding
 * command.  In each case, next points at the character following the
 * command name and the following space.  They each return a pointer
 * to the character terminating the command, and die with an
 * explanatory message if there are any parsing problems.  All of
 * these functions handle either text or binary format input,
 * depending on how line_termination is set.
 */

static const char *parse_cmd_update(struct ref_transaction *transaction,
                                    struct strbuf *input, const char *next)
{
        struct strbuf err = STRBUF_INIT;
        char *refname;
        struct object_id new_oid, old_oid;
        int have_old;

        refname = parse_refname(input, &next);
        if (!refname)
                die("update: missing <ref>");

        if (parse_next_oid(input, &next, &new_oid, "update", refname,
                           PARSE_SHA1_ALLOW_EMPTY))
                die("update %s: missing <newvalue>", refname);

        have_old = !parse_next_oid(input, &next, &old_oid, "update", refname,
                                   PARSE_SHA1_OLD);

        if (*next != line_termination)
                die("update %s: extra input: %s", refname, next);

        if (ref_transaction_update(transaction, refname,
                                   &new_oid, have_old ? &old_oid : NULL,
                                   update_flags | create_reflog_flag,
                                   msg, &err))
                die("%s", err.buf);

        update_flags = default_flags;
        free(refname);
        strbuf_release(&err);

        return next;
}

static const char *parse_cmd_create(struct ref_transaction *transaction,
                                    struct strbuf *input, const char *next)
{
        struct strbuf err = STRBUF_INIT;
        char *refname;
        struct object_id new_oid;

        refname = parse_refname(input, &next);
        if (!refname)
                die("create: missing <ref>");

        if (parse_next_oid(input, &next, &new_oid, "create", refname, 0))
                die("create %s: missing <newvalue>", refname);

        if (is_null_oid(&new_oid))
                die("create %s: zero <newvalue>", refname);

        if (*next != line_termination)
                die("create %s: extra input: %s", refname, next);

        if (ref_transaction_create(transaction, refname, &new_oid,
                                   update_flags | create_reflog_flag,
                                   msg, &err))
                die("%s", err.buf);

        update_flags = default_flags;
        free(refname);
        strbuf_release(&err);

        return next;
}

static const char *parse_cmd_delete(struct ref_transaction *transaction,
                                    struct strbuf *input, const char *next)
{
        struct strbuf err = STRBUF_INIT;
        char *refname;
        struct object_id old_oid;
        int have_old;

        refname = parse_refname(input, &next);
        if (!refname)
                die("delete: missing <ref>");

        if (parse_next_oid(input, &next, &old_oid, "delete", refname,
                           PARSE_SHA1_OLD)) {
                have_old = 0;
        } else {
                if (is_null_oid(&old_oid))
                        die("delete %s: zero <oldvalue>", refname);
                have_old = 1;
        }

        if (*next != line_termination)
                die("delete %s: extra input: %s", refname, next);

        if (ref_transaction_delete(transaction, refname,
                                   have_old ? &old_oid : NULL,
                                   update_flags, msg, &err))
                die("%s", err.buf);

        update_flags = default_flags;
        free(refname);
        strbuf_release(&err);

        return next;
}

static const char *parse_cmd_verify(struct ref_transaction *transaction,
                                    struct strbuf *input, const char *next)
{
        struct strbuf err = STRBUF_INIT;
        char *refname;
        struct object_id old_oid;

        refname = parse_refname(input, &next);
        if (!refname)
                die("verify: missing <ref>");

        if (parse_next_oid(input, &next, &old_oid, "verify", refname,
                           PARSE_SHA1_OLD))
                oidclr(&old_oid);

        if (*next != line_termination)
                die("verify %s: extra input: %s", refname, next);

        if (ref_transaction_verify(transaction, refname, &old_oid,
                                   update_flags, &err))
                die("%s", err.buf);

        update_flags = default_flags;
        free(refname);
        strbuf_release(&err);

        return next;
}

static const char *parse_cmd_option(struct strbuf *input, const char *next)
{
        const char *rest;
        if (skip_prefix(next, "no-deref", &rest) && *rest == line_termination)
                update_flags |= REF_NO_DEREF;
        else
                die("option unknown: %s", next);
        return rest;
}

static void update_refs_stdin(struct ref_transaction *transaction)
{
        struct strbuf input = STRBUF_INIT;
        const char *next;

        if (strbuf_read(&input, 0, 1000) < 0)
                die_errno("could not read from stdin");
        next = input.buf;
        /* Read each line dispatch its command */
        while (next < input.buf + input.len) {
                if (*next == line_termination)
                        die("empty command in input");
                else if (isspace(*next))
                        die("whitespace before command: %s", next);
                else if (skip_prefix(next, "update ", &next))
                        next = parse_cmd_update(transaction, &input, next);
                else if (skip_prefix(next, "create ", &next))
                        next = parse_cmd_create(transaction, &input, next);
                else if (skip_prefix(next, "delete ", &next))
                        next = parse_cmd_delete(transaction, &input, next);
                else if (skip_prefix(next, "verify ", &next))
                        next = parse_cmd_verify(transaction, &input, next);
                else if (skip_prefix(next, "option ", &next))
                        next = parse_cmd_option(&input, next);
                else
                        die("unknown command: %s", next);

                next++;
        }

        strbuf_release(&input);
}

int cmd_update_ref(int argc, const char **argv, const char *prefix)
{
        const char *refname, *oldval;
        struct object_id oid, oldoid;
        int delete = 0, no_deref = 0, read_stdin = 0, end_null = 0;
        int create_reflog = 0;
        struct option options[] = {
                OPT_STRING( 'm', NULL, &msg, N_("reason"), N_("reason of the update")),
                OPT_BOOL('d', NULL, &delete, N_("delete the reference")),
                OPT_BOOL( 0 , "no-deref", &no_deref,
                                        N_("update <refname> not the one it points to")),
                OPT_BOOL('z', NULL, &end_null, N_("stdin has NUL-terminated arguments")),
                OPT_BOOL( 0 , "stdin", &read_stdin, N_("read updates from stdin")),
                OPT_BOOL( 0 , "create-reflog", &create_reflog, N_("create a reflog")),
                OPT_END(),
        };

        git_config(git_default_config, NULL);
        argc = parse_options(argc, argv, prefix, options, git_update_ref_usage,
                             0);
        if (msg && !*msg)
                die("Refusing to perform update with empty message.");

        create_reflog_flag = create_reflog ? REF_FORCE_CREATE_REFLOG : 0;

        if (no_deref) {
                default_flags = REF_NO_DEREF;
                update_flags = default_flags;
        }

        if (read_stdin) {
                struct strbuf err = STRBUF_INIT;
                struct ref_transaction *transaction;

                transaction = ref_transaction_begin(&err);
                if (!transaction)
                        die("%s", err.buf);
                if (delete || argc > 0)
                        usage_with_options(git_update_ref_usage, options);
                if (end_null)
                        line_termination = '\0';
                update_refs_stdin(transaction);
                if (ref_transaction_commit(transaction, &err))
                        die("%s", err.buf);
                ref_transaction_free(transaction);
                strbuf_release(&err);
                return 0;
        }

        if (end_null)
                usage_with_options(git_update_ref_usage, options);

        if (delete) {
                if (argc < 1 || argc > 2)
                        usage_with_options(git_update_ref_usage, options);
                refname = argv[0];
                oldval = argv[1];
        } else {
                const char *value;
                if (argc < 2 || argc > 3)
                        usage_with_options(git_update_ref_usage, options);
                refname = argv[0];
                value = argv[1];
                oldval = argv[2];
                if (get_oid(value, &oid))
                        die("%s: not a valid SHA1", value);
        }

        if (oldval) {
                if (!*oldval)
                        /*
                         * The empty string implies that the reference
                         * must not already exist:
                         */
                        oidclr(&oldoid);
                else if (get_oid(oldval, &oldoid))
                        die("%s: not a valid old SHA1", oldval);
        }

        if (delete)
                /*
                 * For purposes of backwards compatibility, we treat
                 * NULL_SHA1 as "don't care" here:
                 */
                return delete_ref(msg, refname,
                                  (oldval && !is_null_oid(&oldoid)) ? &oldoid : NULL,
                                  default_flags);
        else
                return update_ref(msg, refname, &oid, oldval ? &oldoid : NULL,
                                  default_flags | create_reflog_flag,
                                  UPDATE_REFS_DIE_ON_ERR);
}