#include "cache.h"
#include "diff.h"
#include "commit.h"
#include "log-tree.h"
#include "builtin.h"
#include "submodule.h"

static struct rev_info log_tree_opt;

static int diff_tree_commit_sha1(const struct object_id *oid)
{
        struct commit *commit = lookup_commit_reference(oid->hash);
        if (!commit)
                return -1;
        return log_tree_commit(&log_tree_opt, commit);
}

/* Diff one or more commits. */
static int stdin_diff_commit(struct commit *commit, const char *p)
{
        struct object_id oid;
        struct commit_list **pptr = NULL;

        /* Graft the fake parents locally to the commit */
        while (isspace(*p++) && !parse_oid_hex(p, &oid, &p)) {
                struct commit *parent = lookup_commit(oid.hash);
                if (!pptr) {
                        /* Free the real parent list */
                        free_commit_list(commit->parents);
                        commit->parents = NULL;
                        pptr = &(commit->parents);
                }
                if (parent) {
                        pptr = &commit_list_insert(parent, pptr)->next;
                }
        }
        return log_tree_commit(&log_tree_opt, commit);
}

/* Diff two trees. */
static int stdin_diff_trees(struct tree *tree1, const char *p)
{
        struct object_id oid;
        struct tree *tree2;
        if (!isspace(*p++) || parse_oid_hex(p, &oid, &p) || *p)
                return error("Need exactly two trees, separated by a space");
        tree2 = lookup_tree(oid.hash);
        if (!tree2 || parse_tree(tree2))
                return -1;
        printf("%s %s\n", oid_to_hex(&tree1->object.oid),
                          oid_to_hex(&tree2->object.oid));
        diff_tree_sha1(tree1->object.oid.hash, tree2->object.oid.hash,
                       "", &log_tree_opt.diffopt);
        log_tree_diff_flush(&log_tree_opt);
        return 0;
}

static int diff_tree_stdin(char *line)
{
        int len = strlen(line);
        struct object_id oid;
        struct object *obj;
        const char *p;

        if (!len || line[len-1] != '\n')
                return -1;
        line[len-1] = 0;
        if (parse_oid_hex(line, &oid, &p))
                return -1;
        obj = parse_object(oid.hash);
        if (!obj)
                return -1;
        if (obj->type == OBJ_COMMIT)
                return stdin_diff_commit((struct commit *)obj, p);
        if (obj->type == OBJ_TREE)
                return stdin_diff_trees((struct tree *)obj, p);
        error("Object %s is a %s, not a commit or tree",
              oid_to_hex(&oid), typename(obj->type));
        return -1;
}

static const char diff_tree_usage[] =
"git diff-tree [--stdin] [-m] [-c] [--cc] [-s] [-v] [--pretty] [-t] [-r] [--root] "
"[<common-diff-options>] <tree-ish> [<tree-ish>] [<path>...]\n"
"  -r            diff recursively\n"
"  --root        include the initial commit as diff against /dev/null\n"
COMMON_DIFF_OPTIONS_HELP;

static void diff_tree_tweak_rev(struct rev_info *rev, struct setup_revision_opt *opt)
{
        if (!rev->diffopt.output_format) {
                if (rev->dense_combined_merges)
                        rev->diffopt.output_format = DIFF_FORMAT_PATCH;
                else
                        rev->diffopt.output_format = DIFF_FORMAT_RAW;
        }
}

int cmd_diff_tree(int argc, const char **argv, const char *prefix)
{
        int nr_sha1;
        char line[1000];
        struct object *tree1, *tree2;
        static struct rev_info *opt = &log_tree_opt;
        struct setup_revision_opt s_r_opt;
        int read_stdin = 0;

        init_revisions(opt, prefix);
        gitmodules_config();
        git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
        opt->abbrev = 0;
        opt->diff = 1;
        opt->disable_stdin = 1;
        memset(&s_r_opt, 0, sizeof(s_r_opt));
        s_r_opt.tweak = diff_tree_tweak_rev;

        precompose_argv(argc, argv);
        argc = setup_revisions(argc, argv, opt, &s_r_opt);

        while (--argc > 0) {
                const char *arg = *++argv;

                if (!strcmp(arg, "--stdin")) {
                        read_stdin = 1;
                        continue;
                }
                usage(diff_tree_usage);
        }

        /*
         * NOTE! We expect "a ^b" to be equal to "a..b", so we
         * reverse the order of the objects if the second one
         * is marked UNINTERESTING.
         */
        nr_sha1 = opt->pending.nr;
        switch (nr_sha1) {
        case 0:
                if (!read_stdin)
                        usage(diff_tree_usage);
                break;
        case 1:
                tree1 = opt->pending.objects[0].item;
                diff_tree_commit_sha1(&tree1->oid);
                break;
        case 2:
                tree1 = opt->pending.objects[0].item;
                tree2 = opt->pending.objects[1].item;
                if (tree2->flags & UNINTERESTING) {
                        struct object *tmp = tree2;
                        tree2 = tree1;
                        tree1 = tmp;
                }
                diff_tree_sha1(tree1->oid.hash,
                               tree2->oid.hash,
                               "", &opt->diffopt);
                log_tree_diff_flush(opt);
                break;
        }

        if (read_stdin) {
                int saved_nrl = 0;
                int saved_dcctc = 0;

                if (opt->diffopt.detect_rename)
                        opt->diffopt.setup |= (DIFF_SETUP_USE_SIZE_CACHE |
                                               DIFF_SETUP_USE_CACHE);
                while (fgets(line, sizeof(line), stdin)) {
                        struct object_id oid;

                        if (get_oid_hex(line, &oid)) {
                                fputs(line, stdout);
                                fflush(stdout);
                        }
                        else {
                                diff_tree_stdin(line);
                                if (saved_nrl < opt->diffopt.needed_rename_limit)
                                        saved_nrl = opt->diffopt.needed_rename_limit;
                                if (opt->diffopt.degraded_cc_to_c)
                                        saved_dcctc = 1;
                        }
                }
                opt->diffopt.degraded_cc_to_c = saved_dcctc;
                opt->diffopt.needed_rename_limit = saved_nrl;
        }

        return diff_result_code(&opt->diffopt, 0);
}