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

static struct rev_info log_tree_opt;

static int diff_tree_commit_sha1(const unsigned char *sha1)
{
        struct commit *commit = lookup_commit_reference(sha1);
        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, char *line, int len)
{
        unsigned char sha1[20];
        if (isspace(line[40]) && !get_sha1_hex(line+41, sha1)) {
                /* Graft the fake parents locally to the commit */
                int pos = 41;
                struct commit_list **pptr, *parents;

                /* Free the real parent list */
                for (parents = commit->parents; parents; ) {
                        struct commit_list *tmp = parents->next;
                        free(parents);
                        parents = tmp;
                }
                commit->parents = NULL;
                pptr = &(commit->parents);
                while (line[pos] && !get_sha1_hex(line + pos, sha1)) {
                        struct commit *parent = lookup_commit(sha1);
                        if (parent) {
                                pptr = &commit_list_insert(parent, pptr)->next;
                        }
                        pos += 41;
                }
        }
        return log_tree_commit(&log_tree_opt, commit);
}

/* Diff two trees. */
static int stdin_diff_trees(struct tree *tree1, char *line, int len)
{
        unsigned char sha1[20];
        struct tree *tree2;
        if (len != 82 || !isspace(line[40]) || get_sha1_hex(line + 41, sha1))
                return error("Need exactly two trees, separated by a space");
        tree2 = lookup_tree(sha1);
        if (!tree2 || parse_tree(tree2))
                return -1;
        printf("%s %s\n", sha1_to_hex(tree1->object.sha1),
                          sha1_to_hex(tree2->object.sha1));
        diff_tree_sha1(tree1->object.sha1, tree2->object.sha1,
                       "", &log_tree_opt.diffopt);
        log_tree_diff_flush(&log_tree_opt);
        return 0;
}

static int diff_tree_stdin(char *line)
{
        int len = strlen(line);
        unsigned char sha1[20];
        struct object *obj;

        if (!len || line[len-1] != '\n')
                return -1;
        line[len-1] = 0;
        if (get_sha1_hex(line, sha1))
                return -1;
        obj = lookup_unknown_object(sha1);
        if (!obj || !obj->parsed)
                obj = parse_object(sha1);
        if (!obj)
                return -1;
        if (obj->type == OBJ_COMMIT)
                return stdin_diff_commit((struct commit *)obj, line, len);
        if (obj->type == OBJ_TREE)
                return stdin_diff_trees((struct tree *)obj, line, len);
        error("Object %s is a %s, not a commit or tree",
              sha1_to_hex(sha1), 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);
        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;
        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->sha1);
                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->sha1,
                               tree2->sha1,
                               "", &opt->diffopt);
                log_tree_diff_flush(opt);
                break;
        }

        if (read_stdin) {
                if (opt->diffopt.detect_rename)
                        opt->diffopt.setup |= (DIFF_SETUP_USE_SIZE_CACHE |
                                               DIFF_SETUP_USE_CACHE);
                while (fgets(line, sizeof(line), stdin)) {
                        unsigned char sha1[20];

                        if (get_sha1_hex(line, sha1)) {
                                fputs(line, stdout);
                                fflush(stdout);
                        }
                        else
                                diff_tree_stdin(line);
                }
        }

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