/*
 * Copyright (C) 2006, Fredrik Kuivinen <freku045@student.liu.se>
 */

#include <assert.h>
#include <time.h>
#include <sys/time.h>
#include <math.h>

#include "cache.h"
#include "refs.h"
#include "tag.h"
#include "commit.h"
#include "tree.h"
#include "blob.h"
#include "diff.h"
#include "revision.h"

#define DEBUG 0

static const char blame_usage[] = "[-c] [-l] [--] file [commit]\n"
        "  -c, --compability Use the same output mode as git-annotate (Default: off)\n"
        "  -l, --long        Show long commit SHA1 (Default: off)\n"
        "  -h, --help        This message";

static struct commit **blame_lines;
static int num_blame_lines;
static char* blame_contents;
static int blame_len;

struct util_info {
        int *line_map;
        unsigned char sha1[20]; /* blob sha, not commit! */
        char *buf;
        unsigned long size;
        int num_lines;
//    const char* path;
};

struct chunk {
        int off1, len1; // ---
        int off2, len2; // +++
};

struct patch {
        struct chunk *chunks;
        int num;
};

static void get_blob(struct commit *commit);

/* Only used for statistics */
static int num_get_patch = 0;
static int num_commits = 0;
static int patch_time = 0;

#define TEMPFILE_PATH_LEN 60
static struct patch *get_patch(struct commit *commit, struct commit *other)
{
        struct patch *ret;
        struct util_info *info_c = (struct util_info *)commit->object.util;
        struct util_info *info_o = (struct util_info *)other->object.util;
        char tmp_path1[TEMPFILE_PATH_LEN], tmp_path2[TEMPFILE_PATH_LEN];
        char diff_cmd[TEMPFILE_PATH_LEN*2 + 20];
        struct timeval tv_start, tv_end;
        int fd;
        FILE *fin;
        char buf[1024];

        ret = xmalloc(sizeof(struct patch));
        ret->chunks = NULL;
        ret->num = 0;

        get_blob(commit);
        get_blob(other);

        gettimeofday(&tv_start, NULL);

        fd = git_mkstemp(tmp_path1, TEMPFILE_PATH_LEN, "git-blame-XXXXXX");
        if (fd < 0)
                die("unable to create temp-file: %s", strerror(errno));

        if (xwrite(fd, info_c->buf, info_c->size) != info_c->size)
                die("write failed: %s", strerror(errno));
        close(fd);

        fd = git_mkstemp(tmp_path2, TEMPFILE_PATH_LEN, "git-blame-XXXXXX");
        if (fd < 0)
                die("unable to create temp-file: %s", strerror(errno));

        if (xwrite(fd, info_o->buf, info_o->size) != info_o->size)
                die("write failed: %s", strerror(errno));
        close(fd);

        sprintf(diff_cmd, "diff -u -U 0 %s %s", tmp_path1, tmp_path2);
        fin = popen(diff_cmd, "r");
        if (!fin)
                die("popen failed: %s", strerror(errno));

        while (fgets(buf, sizeof(buf), fin)) {
                struct chunk *chunk;
                char *start, *sp;

                if (buf[0] != '@' || buf[1] != '@')
                        continue;

                if (DEBUG)
                        printf("chunk line: %s", buf);
                ret->num++;
                ret->chunks = xrealloc(ret->chunks,
                                       sizeof(struct chunk) * ret->num);
                chunk = &ret->chunks[ret->num - 1];

                assert(!strncmp(buf, "@@ -", 4));

                start = buf + 4;
                sp = index(start, ' ');
                *sp = '\0';
                if (index(start, ',')) {
                        int ret =
                            sscanf(start, "%d,%d", &chunk->off1, &chunk->len1);
                        assert(ret == 2);
                } else {
                        int ret = sscanf(start, "%d", &chunk->off1);
                        assert(ret == 1);
                        chunk->len1 = 1;
                }
                *sp = ' ';

                start = sp + 1;
                sp = index(start, ' ');
                *sp = '\0';
                if (index(start, ',')) {
                        int ret =
                            sscanf(start, "%d,%d", &chunk->off2, &chunk->len2);
                        assert(ret == 2);
                } else {
                        int ret = sscanf(start, "%d", &chunk->off2);
                        assert(ret == 1);
                        chunk->len2 = 1;
                }
                *sp = ' ';

                if (chunk->len1 == 0)
                        chunk->off1++;
                if (chunk->len2 == 0)
                        chunk->off2++;

                if (chunk->off1 > 0)
                        chunk->off1--;
                if (chunk->off2 > 0)
                        chunk->off2--;

                assert(chunk->off1 >= 0);
                assert(chunk->off2 >= 0);
        }
        pclose(fin);
        unlink(tmp_path1);
        unlink(tmp_path2);

        gettimeofday(&tv_end, NULL);
        patch_time += 1000000 * (tv_end.tv_sec - tv_start.tv_sec) +
                tv_end.tv_usec - tv_start.tv_usec;

        num_get_patch++;
        return ret;
}

static void free_patch(struct patch *p)
{
        free(p->chunks);
        free(p);
}

static int get_blob_sha1_internal(unsigned char *sha1, const char *base,
                                  int baselen, const char *pathname,
                                  unsigned mode, int stage);

static unsigned char blob_sha1[20];
static int get_blob_sha1(struct tree *t, const char *pathname,
                         unsigned char *sha1)
{
        int i;
        const char *pathspec[2];
        pathspec[0] = pathname;
        pathspec[1] = NULL;
        memset(blob_sha1, 0, sizeof(blob_sha1));
        read_tree_recursive(t, "", 0, 0, pathspec, get_blob_sha1_internal);

        for (i = 0; i < 20; i++) {
                if (blob_sha1[i] != 0)
                        break;
        }

        if (i == 20)
                return -1;

        memcpy(sha1, blob_sha1, 20);
        return 0;
}

static int get_blob_sha1_internal(unsigned char *sha1, const char *base,
                                  int baselen, const char *pathname,
                                  unsigned mode, int stage)
{
        if (S_ISDIR(mode))
                return READ_TREE_RECURSIVE;

        memcpy(blob_sha1, sha1, 20);
        return -1;
}

static void get_blob(struct commit *commit)
{
        struct util_info *info = commit->object.util;
        char type[20];

        if (info->buf)
                return;

        info->buf = read_sha1_file(info->sha1, type, &info->size);

        assert(!strcmp(type, "blob"));
}

/* For debugging only */
static void print_patch(struct patch *p)
{
        int i;
        printf("Num chunks: %d\n", p->num);
        for (i = 0; i < p->num; i++) {
                printf("%d,%d %d,%d\n", p->chunks[i].off1, p->chunks[i].len1,
                       p->chunks[i].off2, p->chunks[i].len2);
        }
}

#if 0
/* For debugging only */
static void print_map(struct commit *cmit, struct commit *other)
{
        struct util_info *util = cmit->object.util;
        struct util_info *util2 = other->object.util;

        int i;
        int max =
            util->num_lines >
            util2->num_lines ? util->num_lines : util2->num_lines;
        int num;

        for (i = 0; i < max; i++) {
                printf("i: %d ", i);
                num = -1;

                if (i < util->num_lines) {
                        num = util->line_map[i];
                        printf("%d\t", num);
                } else
                        printf("\t");

                if (i < util2->num_lines) {
                        int num2 = util2->line_map[i];
                        printf("%d\t", num2);
                        if (num != -1 && num2 != num)
                                printf("---");
                } else
                        printf("\t");

                printf("\n");
        }
}
#endif

// p is a patch from commit to other.
static void fill_line_map(struct commit *commit, struct commit *other,
                          struct patch *p)
{
        struct util_info *util = commit->object.util;
        struct util_info *util2 = other->object.util;
        int *map = util->line_map;
        int *map2 = util2->line_map;
        int cur_chunk = 0;
        int i1, i2;

        if (p->num && DEBUG)
                print_patch(p);

        if (DEBUG)
                printf("num lines 1: %d num lines 2: %d\n", util->num_lines,
                       util2->num_lines);

        for (i1 = 0, i2 = 0; i1 < util->num_lines; i1++, i2++) {
                struct chunk *chunk = NULL;
                if (cur_chunk < p->num)
                        chunk = &p->chunks[cur_chunk];

                if (chunk && chunk->off1 == i1) {
                        if (DEBUG && i2 != chunk->off2)
                                printf("i2: %d off2: %d\n", i2, chunk->off2);

                        assert(i2 == chunk->off2);

                        i1--;
                        i2--;
                        if (chunk->len1 > 0)
                                i1 += chunk->len1;

                        if (chunk->len2 > 0)
                                i2 += chunk->len2;

                        cur_chunk++;
                } else {
                        if (i2 >= util2->num_lines)
                                break;

                        if (map[i1] != map2[i2] && map[i1] != -1) {
                                if (DEBUG)
                                        printf("map: i1: %d %d %p i2: %d %d %p\n",
                                               i1, map[i1],
                                               i1 != -1 ? blame_lines[map[i1]] : NULL,
                                               i2, map2[i2],
                                               i2 != -1 ? blame_lines[map2[i2]] : NULL);
                                if (map2[i2] != -1 &&
                                    blame_lines[map[i1]] &&
                                    !blame_lines[map2[i2]])
                                        map[i1] = map2[i2];
                        }

                        if (map[i1] == -1 && map2[i2] != -1)
                                map[i1] = map2[i2];
                }

                if (DEBUG > 1)
                        printf("l1: %d l2: %d i1: %d i2: %d\n",
                               map[i1], map2[i2], i1, i2);
        }
}

static int map_line(struct commit *commit, int line)
{
        struct util_info *info = commit->object.util;
        assert(line >= 0 && line < info->num_lines);
        return info->line_map[line];
}

static int fill_util_info(struct commit *commit, const char *path)
{
        struct util_info *util;
        if (commit->object.util)
                return 0;

        util = xmalloc(sizeof(struct util_info));

        if (get_blob_sha1(commit->tree, path, util->sha1)) {
                free(util);
                return 1;
        } else {
                util->buf = NULL;
                util->size = 0;
                util->line_map = NULL;
                util->num_lines = -1;
                commit->object.util = util;
                return 0;
        }
}

static void alloc_line_map(struct commit *commit)
{
        struct util_info *util = commit->object.util;
        int i;

        if (util->line_map)
                return;

        get_blob(commit);

        util->num_lines = 0;
        for (i = 0; i < util->size; i++) {
                if (util->buf[i] == '\n')
                        util->num_lines++;
        }
        if(util->buf[util->size - 1] != '\n')
                util->num_lines++;

        util->line_map = xmalloc(sizeof(int) * util->num_lines);

        for (i = 0; i < util->num_lines; i++)
                util->line_map[i] = -1;
}

static void init_first_commit(struct commit* commit, const char* filename)
{
        struct util_info* util;
        int i;

        if (fill_util_info(commit, filename))
                die("fill_util_info failed");

        alloc_line_map(commit);

        util = commit->object.util;

        for (i = 0; i < util->num_lines; i++)
                util->line_map[i] = i;
}


static void process_commits(struct rev_info *rev, const char *path,
                            struct commit** initial)
{
        int i;
        struct util_info* util;
        int lines_left;
        int *blame_p;
        int *new_lines;
        int new_lines_len;

        struct commit* commit = get_revision(rev);
        assert(commit);
        init_first_commit(commit, path);

        util = commit->object.util;
        num_blame_lines = util->num_lines;
        blame_lines = xmalloc(sizeof(struct commit *) * num_blame_lines);
        blame_contents = util->buf;
        blame_len = util->size;

        for (i = 0; i < num_blame_lines; i++)
                blame_lines[i] = NULL;

        lines_left = num_blame_lines;
        blame_p = xmalloc(sizeof(int) * num_blame_lines);
        new_lines = xmalloc(sizeof(int) * num_blame_lines);
        do {
                struct commit_list *parents;
                int num_parents;
                struct util_info *util;

                if (DEBUG)
                        printf("\nProcessing commit: %d %s\n", num_commits,
                               sha1_to_hex(commit->object.sha1));

                if (lines_left == 0)
                        return;

                num_commits++;
                memset(blame_p, 0, sizeof(int) * num_blame_lines);
                new_lines_len = 0;
                num_parents = 0;
                for (parents = commit->parents;
                     parents != NULL; parents = parents->next)
                        num_parents++;

                if(num_parents == 0)
                        *initial = commit;

                if(fill_util_info(commit, path))
                        continue;

                alloc_line_map(commit);
                util = commit->object.util;

                for (parents = commit->parents;
                     parents != NULL; parents = parents->next) {
                        struct commit *parent = parents->item;
                        struct patch *patch;

                        if (parse_commit(parent) < 0)
                                die("parse_commit error");

                        if (DEBUG)
                                printf("parent: %s\n",
                                       sha1_to_hex(parent->object.sha1));

                        if(fill_util_info(parent, path)) {
                                num_parents--;
                                continue;
                        }

                        patch = get_patch(parent, commit);
                        alloc_line_map(parent);
                        fill_line_map(parent, commit, patch);

                        for (i = 0; i < patch->num; i++) {
                            int l;
                            for (l = 0; l < patch->chunks[i].len2; l++) {
                                int mapped_line =
                                    map_line(commit, patch->chunks[i].off2 + l);
                                if (mapped_line != -1) {
                                    blame_p[mapped_line]++;
                                    if (blame_p[mapped_line] == num_parents)
                                        new_lines[new_lines_len++] = mapped_line;
                                }
                            }
                        }
                        free_patch(patch);
                }

                if (DEBUG)
                        printf("parents: %d\n", num_parents);

                for (i = 0; i < new_lines_len; i++) {
                        int mapped_line = new_lines[i];
                        if (blame_lines[mapped_line] == NULL) {
                                blame_lines[mapped_line] = commit;
                                lines_left--;
                                if (DEBUG)
                                        printf("blame: mapped: %d i: %d\n",
                                               mapped_line, i);
                        }
                }
        } while ((commit = get_revision(rev)) != NULL);
}

struct commit_info
{
        char* author;
        char* author_mail;
        unsigned long author_time;
        char* author_tz;
};

static void get_commit_info(struct commit* commit, struct commit_info* ret)
{
        int len;
        char* tmp;
        static char author_buf[1024];

        tmp = strstr(commit->buffer, "\nauthor ") + 8;
        len = index(tmp, '\n') - tmp;
        ret->author = author_buf;
        memcpy(ret->author, tmp, len);

        tmp = ret->author;
        tmp += len;
        *tmp = 0;
        while(*tmp != ' ')
                tmp--;
        ret->author_tz = tmp+1;

        *tmp = 0;
        while(*tmp != ' ')
                tmp--;
        ret->author_time = strtoul(tmp, NULL, 10);

        *tmp = 0;
        while(*tmp != ' ')
                tmp--;
        ret->author_mail = tmp + 1;

        *tmp = 0;
}

static const char* format_time(unsigned long time, const char* tz_str)
{
        static char time_buf[128];
        time_t t = time;
        int minutes, tz;
        struct tm *tm;

        tz = atoi(tz_str);
        minutes = tz < 0 ? -tz : tz;
        minutes = (minutes / 100)*60 + (minutes % 100);
        minutes = tz < 0 ? -minutes : minutes;
        t = time + minutes * 60;
        tm = gmtime(&t);

        strftime(time_buf, sizeof(time_buf), "%Y-%m-%d %H:%M:%S ", tm);
        strcat(time_buf, tz_str);
        return time_buf;
}

int main(int argc, const char **argv)
{
        int i;
        struct commit *initial = NULL;
        unsigned char sha1[20];

        const char *filename = NULL, *commit = NULL;
        char filename_buf[256];
        int sha1_len = 8;
        int compability = 0;
        int options = 1;

        int num_args;
        const char* args[10];
        struct rev_info rev;

        struct commit_info ci;
        const char *buf;
        int max_digits;

        const char* prefix = setup_git_directory();

        for(i = 1; i < argc; i++) {
                if(options) {
                        if(!strcmp(argv[i], "-h") ||
                           !strcmp(argv[i], "--help"))
                                usage(blame_usage);
                        else if(!strcmp(argv[i], "-l") ||
                                !strcmp(argv[i], "--long")) {
                                sha1_len = 40;
                                continue;
                        } else if(!strcmp(argv[i], "-c") ||
                                  !strcmp(argv[i], "--compability")) {
                                compability = 1;
                                continue;
                        } else if(!strcmp(argv[i], "--")) {
                                options = 0;
                                continue;
                        } else if(argv[i][0] == '-')
                                usage(blame_usage);
                        else
                                options = 0;
                }

                if(!options) {
                        if(!filename)
                                filename = argv[i];
                        else if(!commit)
                                commit = argv[i];
                        else
                                usage(blame_usage);
                }
        }

        if(!filename)
                usage(blame_usage);
        if(!commit)
                commit = "HEAD";

        if(prefix)
                sprintf(filename_buf, "%s%s", prefix, filename);
        else
                strcpy(filename_buf, filename);
        filename = filename_buf;

        {
                struct commit* c;
                if (get_sha1(commit, sha1))
                        die("get_sha1 failed, commit '%s' not found", commit);
                c = lookup_commit_reference(sha1);

                if (fill_util_info(c, filename)) {
                        printf("%s not found in %s\n", filename, commit);
                        return 1;
                }
        }

        num_args = 0;
        args[num_args++] = NULL;
        args[num_args++] = "--topo-order";
        args[num_args++] = "--remove-empty";
        args[num_args++] = commit;
        args[num_args++] = "--";
        args[num_args++] = filename;
        args[num_args] = NULL;

        setup_revisions(num_args, args, &rev, "HEAD");
        prepare_revision_walk(&rev);
        process_commits(&rev, filename, &initial);

        buf = blame_contents;
        for (max_digits = 1, i = 10; i <= num_blame_lines + 1; max_digits++)
                i *= 10;

        for (i = 0; i < num_blame_lines; i++) {
                struct commit *c = blame_lines[i];
                if (!c)
                        c = initial;

                get_commit_info(c, &ci);
                fwrite(sha1_to_hex(c->object.sha1), sha1_len, 1, stdout);
                if(compability)
                        printf("\t(%10s\t%10s\t%d)", ci.author,
                               format_time(ci.author_time, ci.author_tz), i+1);
                else
                        printf(" (%-15.15s %10s %*d) ", ci.author,
                               format_time(ci.author_time, ci.author_tz),
                               max_digits, i+1);

                if(i == num_blame_lines - 1) {
                        fwrite(buf, blame_len - (buf - blame_contents),
                               1, stdout);
                        if(blame_contents[blame_len-1] != '\n')
                                putc('\n', stdout);
                } else {
                        char* next_buf = index(buf, '\n') + 1;
                        fwrite(buf, next_buf - buf, 1, stdout);
                        buf = next_buf;
                }
        }

        if (DEBUG) {
                printf("num get patch: %d\n", num_get_patch);
                printf("num commits: %d\n", num_commits);
                printf("patch time: %f\n", patch_time / 1000000.0);
                printf("initial: %s\n", sha1_to_hex(initial->object.sha1));
        }

        return 0;
}