#include "builtin.h"
#include "cache.h"
#include "dir.h"
#include "parse-options.h"
#include "string-list.h"
#include "rerere.h"
#include "xdiff/xdiff.h"
#include "xdiff-interface.h"

static const char * const rerere_usage[] = {
        "git rerere [clear | forget path... | status | remaining | diff | gc]",
        NULL,
};

/* these values are days */
static int cutoff_noresolve = 15;
static int cutoff_resolve = 60;

static time_t rerere_created_at(const char *name)
{
        struct stat st;
        return stat(rerere_path(name, "preimage"), &st) ? (time_t) 0 : st.st_mtime;
}

static time_t rerere_last_used_at(const char *name)
{
        struct stat st;
        return stat(rerere_path(name, "postimage"), &st) ? (time_t) 0 : st.st_mtime;
}

static void unlink_rr_item(const char *name)
{
        unlink(rerere_path(name, "thisimage"));
        unlink(rerere_path(name, "preimage"));
        unlink(rerere_path(name, "postimage"));
        rmdir(git_path("rr-cache/%s", name));
}

static int git_rerere_gc_config(const char *var, const char *value, void *cb)
{
        if (!strcmp(var, "gc.rerereresolved"))
                cutoff_resolve = git_config_int(var, value);
        else if (!strcmp(var, "gc.rerereunresolved"))
                cutoff_noresolve = git_config_int(var, value);
        else
                return git_default_config(var, value, cb);
        return 0;
}

static void garbage_collect(struct string_list *rr)
{
        struct string_list to_remove = STRING_LIST_INIT_DUP;
        DIR *dir;
        struct dirent *e;
        int i, cutoff;
        time_t now = time(NULL), then;

        git_config(git_rerere_gc_config, NULL);
        dir = opendir(git_path("rr-cache"));
        if (!dir)
                die_errno("unable to open rr-cache directory");
        while ((e = readdir(dir))) {
                if (is_dot_or_dotdot(e->d_name))
                        continue;

                then = rerere_last_used_at(e->d_name);
                if (then) {
                        cutoff = cutoff_resolve;
                } else {
                        then = rerere_created_at(e->d_name);
                        if (!then)
                                continue;
                        cutoff = cutoff_noresolve;
                }
                if (then < now - cutoff * 86400)
                        string_list_append(&to_remove, e->d_name);
        }
        for (i = 0; i < to_remove.nr; i++)
                unlink_rr_item(to_remove.items[i].string);
        string_list_clear(&to_remove, 0);
}

static int outf(void *dummy, mmbuffer_t *ptr, int nbuf)
{
        int i;
        for (i = 0; i < nbuf; i++)
                if (write_in_full(1, ptr[i].ptr, ptr[i].size) != ptr[i].size)
                        return -1;
        return 0;
}

static int diff_two(const char *file1, const char *label1,
                const char *file2, const char *label2)
{
        xpparam_t xpp;
        xdemitconf_t xecfg;
        xdemitcb_t ecb;
        mmfile_t minus, plus;

        if (read_mmfile(&minus, file1) || read_mmfile(&plus, file2))
                return 1;

        printf("--- a/%s\n+++ b/%s\n", label1, label2);
        fflush(stdout);
        memset(&xpp, 0, sizeof(xpp));
        xpp.flags = 0;
        memset(&xecfg, 0, sizeof(xecfg));
        xecfg.ctxlen = 3;
        ecb.outf = outf;
        xdi_diff(&minus, &plus, &xpp, &xecfg, &ecb);

        free(minus.ptr);
        free(plus.ptr);
        return 0;
}

int cmd_rerere(int argc, const char **argv, const char *prefix)
{
        struct string_list merge_rr = STRING_LIST_INIT_DUP;
        int i, fd, autoupdate = -1, flags = 0;

        struct option options[] = {
                OPT_SET_INT(0, "rerere-autoupdate", &autoupdate,
                        "register clean resolutions in index", 1),
                OPT_END(),
        };

        argc = parse_options(argc, argv, prefix, options, rerere_usage, 0);

        if (autoupdate == 1)
                flags = RERERE_AUTOUPDATE;
        if (autoupdate == 0)
                flags = RERERE_NOAUTOUPDATE;

        if (argc < 1)
                return rerere(flags);

        if (!strcmp(argv[0], "forget")) {
                const char **pathspec;
                if (argc < 2)
                        warning("'git rerere forget' without paths is deprecated");
                pathspec = get_pathspec(prefix, argv + 1);
                return rerere_forget(pathspec);
        }

        fd = setup_rerere(&merge_rr, flags);
        if (fd < 0)
                return 0;

        if (!strcmp(argv[0], "clear")) {
                for (i = 0; i < merge_rr.nr; i++) {
                        const char *name = (const char *)merge_rr.items[i].util;
                        if (!has_rerere_resolution(name))
                                unlink_rr_item(name);
                }
                unlink_or_warn(git_path("MERGE_RR"));
        } else if (!strcmp(argv[0], "gc"))
                garbage_collect(&merge_rr);
        else if (!strcmp(argv[0], "status"))
                for (i = 0; i < merge_rr.nr; i++)
                        printf("%s\n", merge_rr.items[i].string);
        else if (!strcmp(argv[0], "remaining")) {
                rerere_remaining(&merge_rr);
                for (i = 0; i < merge_rr.nr; i++) {
                        if (merge_rr.items[i].util != RERERE_RESOLVED)
                                printf("%s\n", merge_rr.items[i].string);
                        else
                                /* prepare for later call to
                                 * string_list_clear() */
                                merge_rr.items[i].util = NULL;
                }
        } else if (!strcmp(argv[0], "diff"))
                for (i = 0; i < merge_rr.nr; i++) {
                        const char *path = merge_rr.items[i].string;
                        const char *name = (const char *)merge_rr.items[i].util;
                        diff_two(rerere_path(name, "preimage"), path, path, path);
                }
        else
                usage_with_options(rerere_usage, options);

        string_list_clear(&merge_rr, 1);
        return 0;
}