import { z } from "zod";
import { openai, SCRIPT_MODEL } from "@/lib/ai/openai";
import type { StructuredScript, TokenUsage } from "@/lib/ai/types";

export type RepurposeFormat = "blog" | "social_thread" | "newsletter";

const FORMAT_PROMPTS: Record<RepurposeFormat, string> = {
  blog: "Write an engaging, SEO-friendly blog post based on this episode. Include a compelling title and well-structured markdown body with headings and a short conclusion.",
  social_thread:
    "Write a punchy social thread (6–10 posts, numbered) summarizing the episode's best insights. Start with a strong hook. Put the whole thread in the markdown body.",
  newsletter:
    "Write a friendly email newsletter edition about this episode: a subject line as the title, a short intro, 3–4 key takeaways as bullets, and a call-to-action to listen. Markdown body.",
};

const outputSchema = z.object({ title: z.string().min(1), body: z.string().min(1) });
export type RepurposedOutput = z.infer<typeof outputSchema>;

function scriptToText(script: StructuredScript): string {
  return script.sections
    .map((s) => `## ${s.title}\n` + s.turns.map((t) => t.text).join("\n"))
    .join("\n\n");
}

export async function repurposeScript(
  script: StructuredScript,
  format: RepurposeFormat
): Promise<{ content: RepurposedOutput; usage: TokenUsage }> {
  const transcript = scriptToText(script).slice(0, 9000);
  const res = await openai().chat.completions.create({
    model: SCRIPT_MODEL,
    messages: [
      {
        role: "system",
        content:
          "You are a content marketer who repurposes podcast episodes into other formats. Return STRICT JSON: { \"title\": string, \"body\": string } where body is markdown.",
      },
      {
        role: "user",
        content: `${FORMAT_PROMPTS[format]}\n\nEpisode title: ${script.title}\n\nTranscript:\n${transcript}`,
      },
    ],
    response_format: { type: "json_object" },
    temperature: 0.7,
  });
  const content = outputSchema.parse(JSON.parse(res.choices[0]?.message?.content ?? "{}"));
  return {
    content,
    usage: {
      inputTokens: res.usage?.prompt_tokens ?? 0,
      outputTokens: res.usage?.completion_tokens ?? 0,
    },
  };
}