#include "utilities.h"

List* list_new(size_t item_size) {
    List* list = calloc(1, sizeof(List));
    if (!list) { perror("ERROR: memory allocation in new_list failed!"); return NULL; }

    list->items = calloc(LIST_INIT_CAPACITY, item_size);
    if (!list->items) { perror("ERROR: memory allocation in new_list failed!"); free(list); return NULL; }

    list->len = 0;
    list->capacity = LIST_INIT_CAPACITY;
    list->item_size = item_size;
    return list;
}

int list_push(List* list, void* item) {
    if (!list || !item) return 0;

    if (list->len == list->capacity) {
        size_t new_capacity = list->capacity * 2;
        void* new_items = realloc(list->items, new_capacity * list->item_size);
        if (!new_items) { perror("ERROR: memory reallocation failed in list_push!"); return 0; }

        list->items = new_items;
        list->capacity = new_capacity;
    }

    char* dest = (char*)list->items + (list->len * list->item_size);
    memcpy(dest, item, list->item_size);
    list->len++;

    return 1;
}

int list_remove(List* list, const void* key, int (*compare)(const void*, const void*)) {
    if (!list || !key || !compare || list->len == 0) {
        return 0;
    }

    for (size_t i = 0; i < list->len; i++) {
        char* current_item = (char*)list->items + (i * list->item_size);

        if (compare(key, current_item) == 0) {
            for (size_t j = i; j < list->len - 1; j++) {
                char* dest = (char*)list->items + (j * list->item_size);
                char* src = (char*)list->items + ((j + 1) * list->item_size);
                memcpy(dest, src, list->item_size);
            }

            list->len--;
            return 1;
        }
    }

    return 0;
}

void list_free(List* buffer) {
    if (buffer) {
        for (size_t i = 0; i < buffer->len; i++) {
            free(buffer->items[i]);
        }
        free(buffer->items);
        free(buffer);
    }
}

void* binary_search(const void* key, const void* base, size_t num_elements, size_t element_size, int (*compare)(const void*, const void*)) {
    if (!key || !base || !compare || num_elements == 0) {
        return NULL;
    }

    size_t left = 0;
    size_t right = num_elements - 1;

    while (left <= right) {
        size_t mid = left + (right - left) / 2;

        const char* mid_element = (const char*)base + (mid * element_size);

        int cmp = compare(key, mid_element);
 
        if (cmp == 0) {
            return (void*)mid_element;
        }
        else if (cmp < 0) {
            if (mid == 0) break;
            right = mid - 1;
        }
        else {
            left = mid + 1;
        }
    }

    return NULL;
}

void* list_binary_search(List* list, const void* key, int (*compare)(const void*, const void*)) {
    if (!list || !key || !compare) {
        return NULL;
    }

    return binary_search(key, list->items, list->len, list->item_size, compare);
}

StringBuffer* string_buffer_new() {
    return list_new(sizeof(char*));
}

int string_buffer_push(StringBuffer* buffer, char* path) {
    char* path_copy = strdup(path);
    if (!path_copy) {
        perror("ERROR: strdup failed in string_buffer_push!");
        return 0;
    }
    return list_push(buffer, &path_copy);
}

int compare_strings(const void* a, const void* b) {
    const char* s1 = *(const char**)a;
    const char* s2 = *(const char**)b;
    return strcmp(s1,s2);
}

void string_buffer_sort(StringBuffer* buffer) {
    if (!buffer || buffer->len <= 1) {
        return;
    }

    qsort(buffer->items, buffer->len, sizeof(char*), compare_strings);
}

char* string_buffer_search(StringBuffer* buffer, char* path) {
    if (!buffer || !path) return NULL;
    return (char*)list_binary_search(buffer, path, compare_strings);
}

FileInfoBuffer* file_info_buffer_new() {
    return list_new(sizeof(FileInfo));
}

int file_info_buffer_push(FileInfoBuffer* buffer, FileInfo info) {
    return list_push(buffer, &info);
}

void file_info_buffer_free(List* buffer) {
    if (buffer) {
        free(buffer->items);
        free(buffer);
    }
}

int compare_file_info(const void* a, const void* b) {
    const FileInfo* info1 = (const FileInfo*)a;
    const FileInfo* info2 = (const FileInfo*)b;

    return strcmp(info1->name, info2->name);
}

void file_info_buffer_sort(FileInfoBuffer* buffer) {
    if (!buffer || buffer->len <= 1) {
        return;
    }

    qsort(buffer->items, buffer->len, sizeof(FileInfo), compare_file_info);
}

FileInfo* file_info_buffer_search(FileInfoBuffer* buffer, const char* filename) {
    if (!buffer || !filename) return NULL;

    FileInfo search_key = {.mode = 0, .name = (char*)filename};

    return (FileInfo*)list_binary_search(buffer, &search_key, compare_file_info);
}

static int is_dot_or_dotdot(const char* s) {
    return (s[0] == '.' && (s[1] == '\0' || (s[1] == '.' && s[2] == '\0')));
}

static char* join_path(const char* a, const char* b) {
    size_t la = strlen(a);
    size_t lb = strlen(b);
    int need_sep = (la > 0 && a[la - 1] != '/');

    char* s = calloc(la + (need_sep ? 1 : 0) + lb + 1, sizeof(char));
    if (!s) {
        perror("ERROR: calloc failed in join_path!");
        exit(1);
    }

    memcpy(s, a, la);
    size_t p = la;
    if (need_sep) s[p++] = '/';
    memcpy(s + p, b, lb + 1);

    return s;
}

void normalize_path(char* path, char* rel) {
    if (strlen(rel) == 0) return;

    size_t path_len = strlen(path);
    size_t rel_len = strlen(rel);
    int consumers = rel_len / 3;
    int counter = 0;
    size_t latest = 0;

    for (size_t idx = rel_len; idx < path_len; idx++) {
        if (path[idx] == '/') {
            counter++;
            latest = idx;
            if (counter == consumers) break;
        }
        if (path[idx] == '\0') break;
    }

    strcpy(path, path+latest+(counter > 0 ? 1 : 0));
}

// A function that returns the system path of the where the closest merk
// directory to the current working directory is located up in direction to
// the filesystem root
// Mutates relative in place to get the correct amount of ../ in relation to
// the directory which the software was called in
char* find_root(char* relative) {
    char* current_dir = calloc(PATH_MAX, sizeof(char));
    if (!current_dir) {
        perror("ERROR: calloc in find_root failed!");
        return NULL;
    }

    if (!getcwd(current_dir, PATH_MAX)) {
        perror("ERROR: getcwd in find_root failed!");
        free(current_dir);
        return NULL;
    }

    char* search_dir = strdup(current_dir);
    if (!search_dir) {
        perror("ERROR: strdup in find_root failed!");
        free(current_dir);
        return NULL;
    }

    while (1) {
        size_t dir_len = strlen(search_dir);
        size_t merk_path_len = dir_len + strlen("/.merk") + 1;
        char* merk_path = calloc(merk_path_len, sizeof(char));
        if (!merk_path) {
            perror("ERROR: calloc in find_root failed!");
            free(current_dir);
            free(search_dir);
            return NULL;
        }

        snprintf(merk_path, merk_path_len, "%s/.merk", search_dir);

        struct stat st;
        if (stat(merk_path, &st) == 0 && S_ISDIR(st.st_mode)) {
            free(current_dir);
            free(merk_path);
            char* result = strdup(search_dir);
            free(search_dir);
            return result;
        }

        free(merk_path);

        if (strcmp(search_dir, "/") == 0) {
            break;
        }

        char temp[PATH_MAX];
        snprintf(temp, sizeof(temp), "../%s", relative);
        strcpy(relative, temp);

        char* parent = strrchr(search_dir, '/');
        if (parent == search_dir) {
            search_dir[1] = '\0';
        } else if (parent) {
            *parent = '\0';
        } else {
            break;
        }
    }
    free(current_dir);
    free(search_dir);
    printf("ERROR: you are in no merk repository!\nCreate a new repository with merk init\n");
    return NULL;
}

void walk(char* base, char* base_rel, char* rel, FileInfoBuffer* file_infos, int full_repo_path, char* repo_root_path) {
    DIR* dir = opendir(base);
    if (!dir) {
        return;
    }

    struct dirent* de;
    while ((de = readdir(dir)) != NULL) {
        if (is_dot_or_dotdot(de->d_name)) continue;
        if (strcmp(de->d_name, ".merk") == 0) continue;

        char* child_full = join_path(base, de->d_name);
        if (!child_full) {
            perror("ERROR: memory allocation failed in walk!");
            closedir(dir);
            exit(1);
        }

        struct stat st;
        if (lstat(child_full, &st) != 0) {
            free(child_full);
            continue;
        }

        if (S_ISDIR(st.st_mode)) {
            char* new_rel;
            if (rel && rel[0]) {
                new_rel = join_path(rel, de->d_name);
            } else {
                new_rel = strdup(de->d_name);
            }

            if (!new_rel) {
                perror("ERROR: memory allocation failed in walk!");
                free(child_full);
                closedir(dir);
                exit(1);
            }

            walk(child_full, base_rel, new_rel, file_infos, full_repo_path, repo_root_path);
            free(new_rel);
        } else {
            char* relative_path;
            if (rel && rel[0]) {
                relative_path = join_path(rel, de->d_name);
            } else {
                relative_path = strdup(de->d_name);
            }

            if (!relative_path) {
                perror("ERROR: memory allocation failed in walk!");
                free(child_full);
                closedir(dir);
                exit(1);
            }

            if (!full_repo_path) {
                normalize_path(relative_path, base_rel);
                FileInfo info = (FileInfo){.mode=st.st_mode, .name=strdup(relative_path)};
                file_info_buffer_push(file_infos, info);
                free(relative_path);
            }
            else {
                char* repo_path = get_repo_path(repo_root_path, relative_path);
                FileInfo info = (FileInfo){.mode=st.st_mode, .name=strdup(repo_path)};
                file_info_buffer_push(file_infos, info);
                free(relative_path);
                free(repo_path);
            }
        }

        free(child_full);
    }

    closedir(dir);
}

// We assume that path is in the repo
char* get_repo_path(char* repo_root_path, char* path) {
    char* real_path = realpath(path, NULL);
    cut_path(repo_root_path, real_path);

    size_t len = strlen(real_path);
    if (len > 1 && real_path[len - 1] == '/') {
        real_path[len - 1] = '\0';
    }

    return real_path;
}

int is_in_repo(char* repo_root_path, char* path) {
    size_t root_len = strlen(repo_root_path);
    char* path_base = strdup(path);

    path_base[root_len] = '\0';

    int cmp = strcmp(path_base, repo_root_path);
    free(path_base);

    return cmp;
}

void visualize_diff(File* old_version, File* new_version, ActionList* actions) {
    int* deleted_lines = calloc(old_version->lines, sizeof(int));
    int* inserted_lines = calloc(new_version->lines, sizeof(int));

    if (!deleted_lines || !inserted_lines) {
        free(deleted_lines);
        free(inserted_lines);
        return;
    }

    for (uint64_t i = 0; i < actions->len; i++) {
        if (actions->actions[i].type == DELETE) {
            deleted_lines[actions->actions[i].line_original] = 1;
        } else if (actions->actions[i].type == INSERT) {
            inserted_lines[actions->actions[i].line_changed] = 1;
        }
    }

    uint64_t old_idx = 0, new_idx = 0;

    while (old_idx < old_version->lines || new_idx < new_version->lines) {
        // DELETE
        if (old_idx < old_version->lines && deleted_lines[old_idx]) {
            printf("%s%s%4ld      | %s%s\n", RED_BG, BLACK_FG, old_idx+1, old_version->content[old_idx], RESET);
            old_idx++;
        }
        // INSERT
        else if (new_idx < new_version->lines && inserted_lines[new_idx]) {
            printf("%s%s     %4ld | %s%s\n", GREEN_BG, BLACK_FG, new_idx+1, new_version->content[new_idx], RESET);
            new_idx++;
        }
        // STAYS
        else if (old_idx < old_version->lines && new_idx < new_version->lines) {
            printf("%4ld %4ld | %s\n", old_idx+1, new_idx+1, old_version->content[old_idx]);
            old_idx++;
            new_idx++;
        }
        // DELETE
        else if (old_idx < old_version->lines) {
            printf("%s%s%4ld      | %s%s\n", RED_BG, BLACK_FG, old_idx+1, old_version->content[old_idx], RESET);
            old_idx++;
        }
        // INSERT
        else if (new_idx < new_version->lines) {
            printf("%s%s     %4ld | %s%s\n", GREEN_BG, BLACK_FG, new_idx+1, new_version->content[new_idx], RESET);
            new_idx++;
        }
    }

    free(deleted_lines);
    free(inserted_lines);
}

// In this function we assume that base is a prefix of path
// Thus we just need the length of the base to jump ahead in the path
int cut_path(char* base, char* path) {
    size_t base_len = strlen(base);
    if (strlen(path) < base_len) return 0;
    int add = strlen(path) != base_len ? 1 : 0;

    strcpy(path, path+base_len+add);

    if (add) {
        char tmp[PATH_MAX];
        snprintf(tmp, sizeof(tmp), "%s/", path);
        strcpy(path, tmp);
    }

    return 1;
}

// In this function we assume that the end of the base and the beginning of the
// path are the same so we can concat them together at that part
// The path gets mutated in place
void combine_path(char* base, char* path) {
    size_t base_len = 0;

    for (size_t idx = strlen(base); idx > 0; idx--) {
        if (base[idx] == '/') {
            base_len = idx;
            break;
        }
    }

    char tmp[PATH_MAX];
    snprintf(tmp, sizeof(tmp), "%*s/%s", base_len, base, path);
    strcpy(path, tmp);
}

PathType get_path_type(const char* path) {
    struct stat st;
    int rc = stat(path, &st);
    if (rc != 0) {
        return (errno == ENOENT) ? PT_NOEXIST : PT_ERROR;
    }
    if (S_ISREG(st.st_mode))  return PT_FILE;
    if (S_ISDIR(st.st_mode))  return PT_DIR;
    return PT_OTHER;
}

char* get_file_content(char* path) {
    if (!path) return NULL;

    FILE* file = fopen(path, "rb");
    if (!file) { perror("ERROR: could not open file in get_file_content!"); return NULL; }
    if (fseek(file, 0, SEEK_END) != 0) { fclose(file); return NULL; }
    long file_size = ftell(file);
    if (file_size < 0) { perror("ERROR: file size is negative in get_file_content!"); fclose(file); return NULL; }
    if (fseek(file, 0, SEEK_SET) != 0) { fclose(file); return NULL; }
    size_t n = (size_t)file_size;
    char* buf = (char*)calloc(n + 1, 1);
    if (!buf) { fclose(file); return NULL; }

    size_t got = fread(buf, 1, n, file);
    fclose(file);

    buf[got] = '\0';

    return buf;
}

char* get_file_content_with_size(char* path, size_t* size) {
    if (!path || !size) return NULL;

    FILE* file = fopen(path, "rb");
    if (!file) { perror("ERROR: could not open file in get_file_content_with_size!"); return NULL; }
    if (fseek(file, 0, SEEK_END) != 0) { fclose(file); return NULL; }
    long file_size = ftell(file);
    if (file_size < 0) { perror("ERROR: file size is negative in get_file_content_with_size!"); fclose(file); return NULL; }
    if (fseek(file, 0, SEEK_SET) != 0) { fclose(file); return NULL; }
    size_t n = (size_t)file_size;

    char* buf = (char*)malloc(n);
    if (!buf) { fclose(file); return NULL; }

    size_t got = fread(buf, 1, n, file);
    fclose(file);

    *size = got;
    return buf;
}

// Create directory recursively
static int mkdir_recursive(const char *path, mode_t mode) {
    char *path_copy = strdup(path);
    if (!path_copy) return -1;

    char *p = path_copy;

    if (*p == '/') p++;

    while (*p) {
        while (*p && *p != '/') p++;

        char saved = *p;
        *p = '\0';

        if (mkdir(path_copy, mode) == -1 && errno != EEXIST) {
            free(path_copy);
            return -1;
        }

        *p = saved;
        if (*p) p++;
    }

    free(path_copy);
    return 0;
}

// Create default config file
int create_default_config_file(char* config_path) {
    char *dir_path = strdup(config_path);
    if (!dir_path) return -1;

    char *last_slash = strrchr(dir_path, '/');
    if (last_slash) {
        *last_slash = '\0';
        if (mkdir_recursive(dir_path, 0755) < 0) {
            perror("mkdir_recursive");
            free(dir_path);
            return -1;
        }
    }
    free(dir_path);

    FILE *fp = fopen(config_path, "w");
    if (!fp) {
        perror("fopen");
        return -1;
    }

    fprintf(fp, "[user]\n");
    fprintf(fp, "name = \"Your Name\"\n");
    fprintf(fp, "email = \"your.email@example.com\"\n");

    fclose(fp);
    return 0;
}