/*
 * 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 "diffcore.h"
#include "revision.h"
#include "xdiff-interface.h"

#define DEBUG 0

static const char blame_usage[] = "git-blame [-c] [-l] [-t] [-S <revs-file>] [--] file [commit]\n"
        "  -c, --compatibility Use the same output mode as git-annotate (Default: off)\n"
        "  -l, --long          Show long commit SHA1 (Default: off)\n"
        "  -t, --time          Show raw timestamp (Default: off)\n"
        "  -S, --revs-file     Use revisions from revs-file instead of calling git-rev-list\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* pathname;

        void* topo_data;
};

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;
static int num_commits;
static int patch_time;

struct blame_diff_state {
        struct xdiff_emit_state xm;
        struct patch *ret;
};

static void process_u0_diff(void *state_, char *line, unsigned long len)
{
        struct blame_diff_state *state = state_;
        struct chunk *chunk;

        if (len < 4 || line[0] != '@' || line[1] != '@')
                return;

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

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

        if (parse_hunk_header(line, len,
                              &chunk->off1, &chunk->len1,
                              &chunk->off2, &chunk->len2)) {
                state->ret->num--;
                return;
        }

        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);
}

static struct patch *get_patch(struct commit *commit, struct commit *other)
{
        struct blame_diff_state state;
        xpparam_t xpp;
        xdemitconf_t xecfg;
        mmfile_t file_c, file_o;
        xdemitcb_t ecb;
        struct util_info *info_c = (struct util_info *)commit->util;
        struct util_info *info_o = (struct util_info *)other->util;
        struct timeval tv_start, tv_end;

        get_blob(commit);
        file_c.ptr = info_c->buf;
        file_c.size = info_c->size;

        get_blob(other);
        file_o.ptr = info_o->buf;
        file_o.size = info_o->size;

        gettimeofday(&tv_start, NULL);

        xpp.flags = XDF_NEED_MINIMAL;
        xecfg.ctxlen = 0;
        xecfg.flags = 0;
        ecb.outf = xdiff_outf;
        ecb.priv = &state;
        memset(&state, 0, sizeof(state));
        state.xm.consume = process_u0_diff;
        state.ret = xmalloc(sizeof(struct patch));
        state.ret->chunks = NULL;
        state.ret->num = 0;

        xdl_diff(&file_c, &file_o, &xpp, &xecfg, &ecb);

        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 state.ret;
}

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

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

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

        hashcpy(sha1, blob_sha1);
        return 0;
}

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

        if (strncmp(blame_file, base, baselen) ||
            strcmp(blame_file + baselen, pathname))
                return -1;

        hashcpy(blob_sha1, sha1);
        return -1;
}

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

        if (info->buf)
                return;

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

        assert(!strcmp(type, blob_type));
}

/* 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 DEBUG
/* For debugging only */
static void print_map(struct commit *cmit, struct commit *other)
{
        struct util_info *util = cmit->util;
        struct util_info *util2 = other->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->util;
        struct util_info *util2 = other->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],
                                               (void *) (i1 != -1 ? blame_lines[map[i1]] : NULL),
                                               i2, map2[i2],
                                               (void *) (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->util;
        assert(line >= 0 && line < info->num_lines);
        return info->line_map[line];
}

static struct util_info* get_util(struct commit *commit)
{
        struct util_info *util = commit->util;

        if (util)
                return util;

        util = xmalloc(sizeof(struct util_info));
        util->buf = NULL;
        util->size = 0;
        util->line_map = NULL;
        util->num_lines = -1;
        util->pathname = NULL;
        commit->util = util;
        return util;
}

static int fill_util_info(struct commit *commit)
{
        struct util_info *util = commit->util;

        assert(util);
        assert(util->pathname);

        return !!get_blob_sha1(commit->tree, util->pathname, util->sha1);
}

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

        util->pathname = filename;
        if (fill_util_info(commit))
                die("fill_util_info failed");

        alloc_line_map(commit);

        util = commit->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->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))
                        continue;

                alloc_line_map(commit);
                util = commit->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)) {
                                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);
}


static int compare_tree_path(struct rev_info* revs,
                             struct commit* c1, struct commit* c2)
{
        int ret;
        const char* paths[2];
        struct util_info* util = c2->util;
        paths[0] = util->pathname;
        paths[1] = NULL;

        diff_tree_setup_paths(get_pathspec(revs->prefix, paths),
                              &revs->pruning);
        ret = rev_compare_tree(revs, c1->tree, c2->tree);
        diff_tree_release_paths(&revs->pruning);
        return ret;
}


static int same_tree_as_empty_path(struct rev_info *revs, struct tree* t1,
                                   const char* path)
{
        int ret;
        const char* paths[2];
        paths[0] = path;
        paths[1] = NULL;

        diff_tree_setup_paths(get_pathspec(revs->prefix, paths),
                              &revs->pruning);
        ret = rev_same_tree_as_empty(revs, t1);
        diff_tree_release_paths(&revs->pruning);
        return ret;
}

static const char* find_rename(struct commit* commit, struct commit* parent)
{
        struct util_info* cutil = commit->util;
        struct diff_options diff_opts;
        const char *paths[1];
        int i;

        if (DEBUG) {
                printf("find_rename commit: %s ",
                       sha1_to_hex(commit->object.sha1));
                puts(sha1_to_hex(parent->object.sha1));
        }

        diff_setup(&diff_opts);
        diff_opts.recursive = 1;
        diff_opts.detect_rename = DIFF_DETECT_RENAME;
        paths[0] = NULL;
        diff_tree_setup_paths(paths, &diff_opts);
        if (diff_setup_done(&diff_opts) < 0)
                die("diff_setup_done failed");

        diff_tree_sha1(commit->tree->object.sha1, parent->tree->object.sha1,
                       "", &diff_opts);
        diffcore_std(&diff_opts);

        for (i = 0; i < diff_queued_diff.nr; i++) {
                struct diff_filepair *p = diff_queued_diff.queue[i];

                if (p->status == 'R' && !strcmp(p->one->path, cutil->pathname)) {
                        if (DEBUG)
                                printf("rename %s -> %s\n", p->one->path, p->two->path);
                        return p->two->path;
                }
        }

        return 0;
}

static void simplify_commit(struct rev_info *revs, struct commit *commit)
{
        struct commit_list **pp, *parent;

        if (!commit->tree)
                return;

        if (!commit->parents) {
                struct util_info* util = commit->util;
                if (!same_tree_as_empty_path(revs, commit->tree,
                                             util->pathname))
                        commit->object.flags |= TREECHANGE;
                return;
        }

        pp = &commit->parents;
        while ((parent = *pp) != NULL) {
                struct commit *p = parent->item;

                if (p->object.flags & UNINTERESTING) {
                        pp = &parent->next;
                        continue;
                }

                parse_commit(p);
                switch (compare_tree_path(revs, p, commit)) {
                case REV_TREE_SAME:
                        parent->next = NULL;
                        commit->parents = parent;
                        get_util(p)->pathname = get_util(commit)->pathname;
                        return;

                case REV_TREE_NEW:
                {

                        struct util_info* util = commit->util;
                        if (revs->remove_empty_trees &&
                            same_tree_as_empty_path(revs, p->tree,
                                                    util->pathname)) {
                                const char* new_name = find_rename(commit, p);
                                if (new_name) {
                                        struct util_info* putil = get_util(p);
                                        if (!putil->pathname)
                                                putil->pathname = strdup(new_name);
                                } else {
                                        *pp = parent->next;
                                        continue;
                                }
                        }
                }

                /* fallthrough */
                case REV_TREE_DIFFERENT:
                        pp = &parent->next;
                        if (!get_util(p)->pathname)
                                get_util(p)->pathname =
                                        get_util(commit)->pathname;
                        continue;
                }
                die("bad tree compare for commit %s",
                    sha1_to_hex(commit->object.sha1));
        }
        commit->object.flags |= TREECHANGE;
}


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 = strchr(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,
                               int show_raw_time)
{
        static char time_buf[128];
        time_t t = time;
        int minutes, tz;
        struct tm *tm;

        if (show_raw_time) {
                sprintf(time_buf, "%lu %s", time, tz_str);
                return time_buf;
        }

        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;
}

static void topo_setter(struct commit* c, void* data)
{
        struct util_info* util = c->util;
        util->topo_data = data;
}

static void* topo_getter(struct commit* c)
{
        struct util_info* util = c->util;
        return util->topo_data;
}

static int read_ancestry(const char *graft_file,
                         unsigned char **start_sha1)
{
        FILE *fp = fopen(graft_file, "r");
        char buf[1024];
        if (!fp)
                return -1;
        while (fgets(buf, sizeof(buf), fp)) {
                /* The format is just "Commit Parent1 Parent2 ...\n" */
                int len = strlen(buf);
                struct commit_graft *graft = read_graft_line(buf, len);
                register_commit_graft(graft, 0);
                if (!*start_sha1)
                        *start_sha1 = graft->sha1;
        }
        fclose(fp);
        return 0;
}

int main(int argc, const char **argv)
{
        int i;
        struct commit *initial = NULL;
        unsigned char sha1[20], *sha1_p = NULL;

        const char *filename = NULL, *commit = NULL;
        char filename_buf[256];
        int sha1_len = 8;
        int compatibility = 0;
        int show_raw_time = 0;
        int options = 1;
        struct commit* start_commit;

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

        struct commit_info ci;
        const char *buf;
        int max_digits;
        int longest_file, longest_author;
        int found_rename;

        const char* prefix = setup_git_directory();
        git_config(git_default_config);

        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], "--compatibility")) {
                                compatibility = 1;
                                continue;
                        } else if(!strcmp(argv[i], "-t") ||
                                  !strcmp(argv[i], "--time")) {
                                show_raw_time = 1;
                                continue;
                        } else if(!strcmp(argv[i], "-S")) {
                                if (i + 1 < argc &&
                                    !read_ancestry(argv[i + 1], &sha1_p)) {
                                        compatibility = 1;
                                        i++;
                                        continue;
                                }
                                usage(blame_usage);
                        } 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 && sha1_p)
                usage(blame_usage);
        else if(!commit)
                commit = "HEAD";

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

        if (!sha1_p) {
                if (get_sha1(commit, sha1))
                        die("get_sha1 failed, commit '%s' not found", commit);
                sha1_p = sha1;
        }
        start_commit = lookup_commit_reference(sha1_p);
        get_util(start_commit)->pathname = filename;
        if (fill_util_info(start_commit)) {
                printf("%s not found in %s\n", filename, commit);
                return 1;
        }


        init_revisions(&rev, setup_git_directory());
        rev.remove_empty_trees = 1;
        rev.topo_order = 1;
        rev.prune_fn = simplify_commit;
        rev.topo_setter = topo_setter;
        rev.topo_getter = topo_getter;
        rev.parents = 1;
        rev.limited = 1;

        commit_list_insert(start_commit, &rev.commits);

        args[0] = filename;
        args[1] = NULL;
        diff_tree_setup_paths(args, &rev.pruning);
        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;

        longest_file = 0;
        longest_author = 0;
        found_rename = 0;
        for (i = 0; i < num_blame_lines; i++) {
                struct commit *c = blame_lines[i];
                struct util_info* u;
                if (!c)
                        c = initial;
                u = c->util;

                if (!found_rename && strcmp(filename, u->pathname))
                        found_rename = 1;
                if (longest_file < strlen(u->pathname))
                        longest_file = strlen(u->pathname);
                get_commit_info(c, &ci);
                if (longest_author < strlen(ci.author))
                        longest_author = strlen(ci.author);
        }

        for (i = 0; i < num_blame_lines; i++) {
                struct commit *c = blame_lines[i];
                struct util_info* u;

                if (!c)
                        c = initial;

                u = c->util;
                get_commit_info(c, &ci);
                fwrite(sha1_to_hex(c->object.sha1), sha1_len, 1, stdout);
                if(compatibility) {
                        printf("\t(%10s\t%10s\t%d)", ci.author,
                               format_time(ci.author_time, ci.author_tz,
                                           show_raw_time),
                               i+1);
                } else {
                        if (found_rename)
                                printf(" %-*.*s", longest_file, longest_file,
                                       u->pathname);
                        printf(" (%-*.*s %10s %*d) ",
                               longest_author, longest_author, ci.author,
                               format_time(ci.author_time, ci.author_tz,
                                           show_raw_time),
                               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 = strchr(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;
}