/**
 * write_calibration.ts — Tetlock's primary writer.
 *
 * UPDATEs public.hypotheses (posterior + confidence_band + reviewed_by +
 * updated_at) and APPENDS (or replaces) a "## Calibration history" section
 * to the H-NNNN.md case file. Each calibration includes a timestamp +
 * old/new posterior + recommended_action + rationale.
 */
import { readFile, writeFile } from "node:fs/promises";
import path from "node:path";
import { audit } from "../lib/audit";
import { env } from "../lib/env";
import { query, queryOne } from "../lib/pg";

export interface WriteCalibrationArgs {
  hypothesis_id: string;
  new_posterior: number;
  new_confidence_band: "high" | "medium" | "low" | "speculation";
  delta: number;
  rationale: string;
  recommended_action: "keep" | "downgrade" | "upgrade" | "supersede";
  supersede_reason?: string;
  /** previous posterior captured at call time — used in the case-file row. */
  old_posterior: number | null;
  old_confidence_band: string | null;
}

export interface WriteCalibrationContext {
  job_id: string;
  detective: string;
}

const SECTION_MARKER = "## Calibration history";

function bandFromPosterior(p: number): "high" | "medium" | "low" | "speculation" {
  if (p >= 0.90) return "high";
  if (p >= 0.60) return "medium";
  if (p >= 0.30) return "low";
  return "speculation";
}

function buildSection(args: WriteCalibrationArgs, ctx: WriteCalibrationContext): string {
  const ts = new Date().toISOString();
  const rows = [
    `### ${ts} — ${args.recommended_action}`,
    "",
    `_Calibrated by ${ctx.detective} — job \`${ctx.job_id}\`._`,
    "",
    `| field | old | new |`,
    `|---|---|---|`,
    `| posterior | ${args.old_posterior ?? "—"} | **${args.new_posterior}** |`,
    `| band | ${args.old_confidence_band ?? "—"} | **${args.new_confidence_band}** |`,
    `| delta | — | ${args.delta >= 0 ? "+" : ""}${args.delta.toFixed(3)} |`,
    "",
    `**Rationale.** ${args.rationale}`,
  ];
  if (args.recommended_action === "supersede" && args.supersede_reason) {
    rows.push("", `**Supersede reason.** ${args.supersede_reason}`);
  }
  rows.push("");
  return rows.join("\n");
}

function appendCalibration(existing: string, section: string): string {
  // Calibration history is APPEND-only (Tetlock can be invoked many times
  // and each datapoint matters). Find the section, append; create it if
  // missing.
  const idx = existing.indexOf(`\n${SECTION_MARKER}`);
  if (idx === -1) {
    return existing.trimEnd() + "\n\n" + SECTION_MARKER + "\n\n" + section;
  }
  return existing.trimEnd() + "\n" + section;
}

export async function writeCalibration(
  body: WriteCalibrationArgs,
  ctx: WriteCalibrationContext,
): Promise<{ hypothesis_id: string; case_file: string; new_posterior: number; recommended_action: string }> {
  if (!body.hypothesis_id?.match(/^H-\d{4}$/)) {
    throw new Error(`bad hypothesis_id: ${body.hypothesis_id}`);
  }
  if (!Number.isFinite(body.new_posterior) || body.new_posterior < 0 || body.new_posterior > 1) {
    throw new Error(`new_posterior out of range: ${body.new_posterior}`);
  }
  const expectedBand = bandFromPosterior(body.new_posterior);
  // Force the band to match the posterior — Tetlock can mis-label.
  body.new_confidence_band = expectedBand;
  if (!body.rationale?.trim()) throw new Error("rationale required");
  // Soft cap: 1200 chars. Tetlock often writes 600-800 of substantive
  // reasoning + chunk citations; the prompt asks for ≤ 600 but a 2× slack
  // beats failing the job on an honest analysis.
  if (body.rationale.length > 1200) throw new Error(`rationale too long (${body.rationale.length} > 1200)`);

  const action = body.recommended_action;
  if (!["keep", "downgrade", "upgrade", "supersede"].includes(action)) {
    throw new Error(`bad recommended_action: ${action}`);
  }
  if (action === "supersede" && !body.supersede_reason?.trim()) {
    throw new Error("supersede_reason required when action == supersede");
  }

  // Verify hypothesis exists.
  const h = await queryOne<{ hypothesis_id: string; status: string }>(
    `SELECT hypothesis_id, status FROM public.hypotheses WHERE hypothesis_id = $1`,
    [body.hypothesis_id],
  );
  if (!h) throw new Error(`hypothesis not found: ${body.hypothesis_id}`);

  // UPDATE DB: posterior + band (always), status='superseded' when action=='supersede'.
  if (action === "supersede") {
    await query(
      `UPDATE public.hypotheses
          SET posterior = $1, confidence_band = $2, status = 'superseded',
              reviewed_by = $3, updated_at = NOW()
        WHERE hypothesis_id = $4`,
      [body.new_posterior, body.new_confidence_band, ctx.detective, body.hypothesis_id],
    );
  } else if (action === "keep" && Math.abs(body.delta) < 0.005) {
    // Pure keep with no movement — only touch updated_at + reviewed_by.
    await query(
      `UPDATE public.hypotheses
          SET reviewed_by = $1, updated_at = NOW()
        WHERE hypothesis_id = $2`,
      [ctx.detective, body.hypothesis_id],
    );
  } else {
    await query(
      `UPDATE public.hypotheses
          SET posterior = $1, confidence_band = $2,
              reviewed_by = $3, updated_at = NOW()
        WHERE hypothesis_id = $4`,
      [body.new_posterior, body.new_confidence_band, ctx.detective, body.hypothesis_id],
    );
  }

  // Append calibration row to the case file.
  const file = path.join(env.CASE_ROOT, "hypotheses", `${body.hypothesis_id}.md`);
  let existing: string;
  try {
    existing = await readFile(file, "utf-8");
  } catch (e) {
    throw new Error(`hypothesis case file missing: ${file} (${(e as Error).message})`);
  }
  const section = buildSection(body, ctx);
  const next = appendCalibration(existing, section);
  await writeFile(file, next, "utf-8");

  await audit({
    event: "write_calibration",
    job_id: ctx.job_id,
    detective: ctx.detective,
    hypothesis_id: body.hypothesis_id,
    new_posterior: body.new_posterior,
    new_confidence_band: body.new_confidence_band,
    delta: body.delta,
    recommended_action: action,
    file,
  });

  return {
    hypothesis_id: body.hypothesis_id, case_file: file,
    new_posterior: body.new_posterior,
    recommended_action: action,
  };
}