import { z } from "zod";

const fraction = z.number().finite().min(0).max(1);
export const videoTimeRangeSchema = z
  .object({ start: fraction, end: fraction })
  .refine((range) => range.end > range.start, "结束位置必须晚于开始位置");
export type VideoTimeRange = z.infer<typeof videoTimeRangeSchema>;

export const videoProcessSchema = z.discriminatedUnion("operation", [
  z.object({
    operation: z.literal("crop"),
    url: z.string().url(),
    rect: z
      .object({
        x: fraction,
        y: fraction,
        width: fraction.positive(),
        height: fraction.positive(),
      })
      .refine(
        (rect) => rect.x + rect.width <= 1.001 && rect.y + rect.height <= 1.001,
        "裁剪区域超出画面",
      ),
  }),
  z.object({ operation: z.literal("audio-video"), url: z.string().url() }),
  z.object({
    operation: z.literal("frame"),
    url: z.string().url(),
    kind: z.enum(["first", "last", "current"]),
    time: z.number().finite().min(0).default(0),
  }),
  z.object({
    operation: z.literal("slow"),
    url: z.string().url(),
    factor: z.union([z.literal(2), z.literal(3), z.literal(5)]),
  }),
  z.object({ operation: z.literal("trim"), url: z.string().url(), range: videoTimeRangeSchema }),
]);

export function toVideoTimeRange(range: VideoTimeRange, duration: number) {
  if (!videoTimeRangeSchema.safeParse(range).success || !Number.isFinite(duration) || duration <= 0)
    throw new Error("剪辑范围无效");
  const start = range.start * duration;
  const end = range.end * duration;
  if (end - start < 0.1) throw new Error("剪辑时长不能少于 0.1 秒");
  return { start, end, duration: end - start };
}