import { NEXT_FRAME_PROMPT_TEMPLATE } from "./config.js";

const OPENROUTER_URL = "https://openrouter.ai/api/v1/chat/completions";

const SYSTEM_PROMPT = [
  "You generate a single image per request for an animation pipeline.",
  "Keep style consistency across frames.",
  "No text overlays, no labels, no typography.",
  "Output only the image.",
].join(" ");

function buildFramePrompt({
  masterPrompt,
  userPrompt,
  frameCount,
  frameIndex,
}) {
  const lines = [
    `Create frame ${frameIndex} of ${frameCount} for an animated GIF.`,
    `Concept: ${userPrompt}.`,
    `Master style lock: ${masterPrompt}.`,
    "Use a white background and clean black line doodle style.",
    "Keep the subject identity and scene composition coherent between frames.",
  ];

  if (frameIndex === 1) {
    lines.push("This is the first frame. Establish a clear starting pose.");
  } else {
    lines.push(NEXT_FRAME_PROMPT_TEMPLATE(frameCount));
    lines.push(
      `This is frame ${frameIndex}. Advance the motion naturally from the prior frame references.`
    );
  }

  lines.push("Return one meaningful image only.");
  return lines.join("\n");
}

function buildUserContent(promptText, previousFrames = []) {
  const parts = [{ type: "text", text: promptText }];

  for (const frame of previousFrames.slice(-2)) {
    parts.push({
      type: "image_url",
      image_url: { url: frame },
    });
  }

  return parts;
}

function extractImageUrl(json) {
  const message = json?.choices?.[0]?.message;
  const image = message?.images?.[0];
  return image?.image_url?.url || image?.imageUrl?.url || "";
}

function extractErrorMessage(text, status, fallbackStatusText) {
  try {
    const parsed = JSON.parse(text);
    return (
      parsed?.error?.message ||
      parsed?.message ||
      `Request failed (${status} ${fallbackStatusText})`
    );
  } catch {
    return text || `Request failed (${status} ${fallbackStatusText})`;
  }
}

export async function requestFrameImage({
  apiKey,
  model,
  userPrompt,
  masterPrompt,
  frameCount,
  frameIndex,
  previousFrames,
  imageSize,
  aspectRatio,
}) {
  const promptText = buildFramePrompt({
    masterPrompt,
    userPrompt,
    frameCount,
    frameIndex,
  });

  const body = {
    model,
    stream: false,
    modalities: ["image"],
    messages: [
      { role: "system", content: SYSTEM_PROMPT },
      {
        role: "user",
        content: buildUserContent(promptText, previousFrames),
      },
    ],
    image_config: {
      image_size: imageSize,
      aspect_ratio: aspectRatio,
    },
  };

  const headers = {
    Authorization: `Bearer ${apiKey}`,
    "Content-Type": "application/json",
  };

  if (typeof window !== "undefined" && window.location?.origin?.startsWith("http")) {
    headers["HTTP-Referer"] = window.location.origin;
    headers["X-OpenRouter-Title"] = "vibegif.lol";
  }

  const response = await fetch(OPENROUTER_URL, {
    method: "POST",
    headers,
    body: JSON.stringify(body),
  });

  if (!response.ok) {
    const raw = await response.text();
    throw new Error(
      extractErrorMessage(raw, response.status, response.statusText)
    );
  }

  const json = await response.json();
  const imageUrl = extractImageUrl(json);

  if (!imageUrl) {
    throw new Error("No image returned by model. Try again with fewer frames or simpler prompt.");
  }

  return imageUrl;
}