import { promises as fs } from "node:fs";
import { fileURLToPath } from "node:url";
import { dirname, join } from "node:path";

const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);
const PROMPTS_DIR = join(__dirname, "../../prompts");

/** Available prompt versions */
export const PROMPT_VERSIONS = ["v0.1", "v0.2", "v0.3"];

/** Default prompt version (override via RECONSTRUCTION_PROMPT_VERSION env var) */
const defaultVersionFromEnv = process.env.RECONSTRUCTION_PROMPT_VERSION;
export const DEFAULT_PROMPT_VERSION =
  defaultVersionFromEnv && PROMPT_VERSIONS.includes(defaultVersionFromEnv)
    ? defaultVersionFromEnv
    : "v0.3";

/** Build a v0.1 (extraction-only) prompt inline for backward compatibility */
function buildV1Prompt(scenario) {
  return `You are a neutral analyst performing an evidence-based reconstruction of the following scenario.

Rules:
1. Do NOT invent facts. Only include information present in the scenario or clearly implied.
2. Distinguish carefully between:
   - Direct observations (you witnessed directly)
   - Reported claims (statements made by another person/entity)
   - Interpretations (your analysis of what something means)
   - Unsupported assumptions (things you are guessing without evidence)
3. If information is unknown, place it under "openUncertainties" — never guess.
4. Be precise, concise, and grounded in the text.

Scenario:
${scenario}

Return valid JSON matching this structure exactly:
{
  "observations": [{"id": "...", "description": "...", "confidence": "low|medium|high"}],
  "reportedClaims": [{"id": "...", "description": "...", "confidence": "low|medium|high", "attributedTo": "person/entity or null"}],
  "assumptions": [{"id": "...", "description": "...", "confidence": "low|medium|high"}],
  "entities": [{"id": "...", "description": "...", "confidence": "low|medium|high"}],
  "transitions": [{"id": "...", "description": "...", "confidence": "low|medium|high", "entity": "...", "previousState": "...", "currentState": "...", "explanationStatus": "..."}],
  "expectedButMissing": [{"id": "...", "description": "...", "confidence": "low|medium|high"}],
  "presentButUnexpected": [{"id": "...", "description": "...", "confidence": "low|medium|high"}],
  "contradictions": [{"id": "...", "description": "...", "confidence": "low|medium|high"}],
  "openUncertainties": [{"id": "...", "description": "...", "confidence": "low|medium|high"}]
}

Return ONLY the JSON object. No markdown, no explanation, no preamble.`;
}

/** Load a versioned prompt from disk and substitute {{SCENARIO}} */
async function buildV2Prompt(scenario) {
  try {
    const content = await fs.readFile(
      join(PROMPTS_DIR, "reconstruct-v0.2.md"),
      "utf-8",
    );
    return content.replace("{{SCENARIO}}", scenario);
  } catch {
    // Fall back to v0.1 prompt if v0.2 file is missing
    return buildV1Prompt(scenario);
  }
}

/** Load a versioned prompt from disk and substitute {{SCENARIO}} */
async function buildV3Prompt(scenario) {
  try {
    const content = await fs.readFile(
      join(PROMPTS_DIR, "reconstruct-v0.3.md"),
      "utf-8",
    );
    return content.replace("{{SCENARIO}}", scenario);
  } catch {
    // Fall back to v0.2 prompt if v0.3 file is missing
    return buildV2Prompt(scenario);
  }
}

/**
 * Build an analysis prompt for the given version.
 * @param {"v0.1" | "v0.2" | "v0.3"} [version="v0.3"]
 * @returns {Promise<{prompt: string, version: string}>}
 */
export async function buildPrompt(scenario, version = "v0.3") {
  let prompt;
  switch (version) {
    case "v0.1":
      prompt = buildV1Prompt(scenario);
      break;
    case "v0.2":
      prompt = await buildV2Prompt(scenario);
      break;
    default: // v0.3
      prompt = await buildV3Prompt(scenario);
      break;
  }

  const strongJsonHint =
    "\n\nReturn ONLY a valid JSON object starting with { and ending with }. Do NOT include any text before the opening brace or after the closing brace. Do NOT wrap in markdown backticks.";
  return { prompt: prompt + strongJsonHint, version };
}