/**
 * 识别各驱动常见的「唯一 / 重复键」错误，供任意 service 复用。
 * 具体业务（如用户名冲突 vs 主键重试）用 {@link uniqueConstraintTouchesField} 再区分即可。
 */

/** 遍历包装错误（如 Drizzle）与底层驱动的整条 cause 链 */
export function* eachErrorInChain(err: unknown): Generator<Error> {
    let current: unknown = err;
    const seen = new Set<unknown>();
    while (current instanceof Error && !seen.has(current)) {
        seen.add(current);
        yield current;
        current = "cause" in current ? (current as { cause?: unknown }).cause : undefined;
    }
}

function escapeRegExp(s: string) {
    return s.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
}

/**
 * 报错文案或 constraint 名是否涉及该字段。
 * message 用词边界，避免 `guid` 误匹配 `id`；constraint 多为 `users_username_key` 式拼接，用子串匹配。
 */
export function uniqueConstraintTouchesField(err: unknown, field: string): boolean {
    const fl = field.toLowerCase();
    const re = new RegExp(`\\b${escapeRegExp(field)}\\b`, "i");
    for (const e of eachErrorInChain(err)) {
        if (re.test(e.message)) {
            return true;
        }
        if ("constraint" in e) {
            const c = String((e as { constraint?: unknown }).constraint ?? "").toLowerCase();
            if (c.includes(fl)) {
                return true;
            }
        }
    }
    return false;
}

export function isUniqueConstraintViolation(err: unknown): boolean {
    for (const e of eachErrorInChain(err)) {
        const code = "code" in e ? String((e as { code?: unknown }).code ?? "") : "";
        const errno = "errno" in e ? (e as { errno?: unknown }).errno : undefined;

        if (code === "23505") {
            return true;
        }
        if (code === "ER_DUP_ENTRY") {
            return true;
        }
        if (typeof errno === "number" && errno === 1062) {
            return true;
        }
        if (code.startsWith("SQLITE_CONSTRAINT")) {
            return true;
        }

        const m = e.message.toLowerCase();
        if (m.includes("unique constraint failed")) {
            return true;
        }
        if (m.includes("duplicate entry")) {
            return true;
        }
        if (m.includes("duplicate key") && m.includes("unique")) {
            return true;
        }
    }
    return false;
}

/** 唯一冲突且与指定字段相关（例如用户名占用） */
export function isUniqueConflictOnField(err: unknown, field: string): boolean {
    return isUniqueConstraintViolation(err) && uniqueConstraintTouchesField(err, field);
}

/** 唯一冲突且与指定字段无关（例如除 username 外仅有主键时的 id 撞车重试） */
export function isUniqueConflictExceptField(err: unknown, field: string): boolean {
    return isUniqueConstraintViolation(err) && !uniqueConstraintTouchesField(err, field);
}