// build_evidence_index.ts — materialize EvidenceRecord rows from
// source JSONL streams. Pure mechanical view: every output row traces
// to a single source row via provenance.{source_file, line_offset,
// sig_hash}.
//
// USAGE
//   bun run scripts/distillation/build_evidence_index.ts            # materialize, write outputs
//   bun run scripts/distillation/build_evidence_index.ts --dry-run  # count + report, no writes
//   LH_DISTILL_ROOT=/path bun run ...                               # override repo root (tests)
//
// OUTPUTS
//   data/evidence/YYYY/MM/DD/<source-stem>.jsonl    valid records
//   data/_kb/distillation_skips.jsonl                rows that failed validation (append)
//   reports/distillation/<ts>/receipt.json           per-run audit (Receipt schema)
//
// IDEMPOTENCY
//   sig_hash = canonicalSha256(orderedKeys(source_row)). Re-running
//   loads existing day-partition output files into a seen set, so
//   already-materialized rows are skipped (not duplicated). Bit-stable
//   on identical input.
//
// NON-NEGOTIABLES (per spec + recon)
//   - ZERO model calls — deterministic only
//   - Provenance on every emitted row (the schema validator enforces it)
//   - Empty/missing source files do not error — they're tallied as
//     "rows_present: false" in the receipt
//   - Validator rejection ≠ runtime error — invalid rows go to skips
//     with their full error list, materialization continues

import { existsSync, readFileSync, mkdirSync, writeFileSync, readdirSync, appendFileSync, statSync } from "node:fs";
import { resolve, dirname } from "node:path";
import { spawnSync } from "node:child_process";

import { TRANSFORMS, canonicalSha256, type TransformDef } from "./transforms";
import { validateEvidenceRecord } from "../../auditor/schemas/distillation/evidence_record";
import { RECEIPT_SCHEMA_VERSION, validateReceipt, type Receipt, type FileReference } from "../../auditor/schemas/distillation/receipt";

const DEFAULT_ROOT = process.env.LH_DISTILL_ROOT ?? "/home/profit/lakehouse";

export interface MaterializeOptions {
  root: string;                  // repo root — source jsonls + outputs are relative to this
  transforms: TransformDef[];    // override for tests
  recorded_at: string;           // ISO 8601 — fixed for the run, used in provenance
  dry_run?: boolean;             // count but don't write
}

export interface SourceResult {
  source_file_relpath: string;
  rows_present: boolean;
  rows_read: number;
  rows_written: number;
  rows_skipped: number;
  rows_deduped: number;
  output_files: string[];
}

export interface MaterializeResult {
  sources: SourceResult[];
  totals: {
    rows_read: number;
    rows_written: number;
    rows_skipped: number;
    rows_deduped: number;
  };
  receipt: Receipt;
  receipt_path: string;
  evidence_dir: string;
  skips_path: string;
}

const ISO_DATE_PARTITION = (iso: string): string => {
  const d = new Date(iso);
  return `${d.getUTCFullYear()}/${String(d.getUTCMonth() + 1).padStart(2, "0")}/${String(d.getUTCDate()).padStart(2, "0")}`;
};

const OUTPUT_STEM = (source_file_relpath: string): string => {
  const m = source_file_relpath.match(/([^/]+)\.jsonl$/);
  return m ? m[1] : source_file_relpath.replace(/[^a-z0-9_]/gi, "_");
};

function sha256OfFile(path: string): string {
  const hasher = new Bun.CryptoHasher("sha256");
  hasher.update(readFileSync(path));
  return hasher.digest("hex");
}

function getGitSha(root: string): string {
  const r = spawnSync("git", ["-C", root, "rev-parse", "HEAD"], { encoding: "utf8" });
  if (r.status !== 0) return "0".repeat(40);
  return r.stdout.trim();
}

function getGitBranch(root: string): string | undefined {
  const r = spawnSync("git", ["-C", root, "rev-parse", "--abbrev-ref", "HEAD"], { encoding: "utf8" });
  return r.status === 0 ? r.stdout.trim() : undefined;
}

function getGitDirty(root: string): boolean {
  const r = spawnSync("git", ["-C", root, "status", "--porcelain"], { encoding: "utf8" });
  return r.status === 0 && r.stdout.trim().length > 0;
}

// Load sig_hashes already present in the target day-partition output
// file. Used to skip records that a prior run of the same day already
// materialized — keeps the materializer idempotent across reruns.
function loadSeenHashes(out_path: string): Set<string> {
  const seen = new Set<string>();
  if (!existsSync(out_path)) return seen;
  for (const line of readFileSync(out_path, "utf8").split("\n")) {
    if (!line) continue;
    try {
      const row = JSON.parse(line);
      if (row?.provenance?.sig_hash) seen.add(row.provenance.sig_hash);
    } catch {
      // Malformed line — ignore. Will be overwritten on next valid hash collision.
    }
  }
  return seen;
}

async function processSource(
  transform: TransformDef,
  opts: MaterializeOptions,
  evidence_dir: string,
  skips_path: string,
): Promise<SourceResult> {
  const source_path = resolve(opts.root, transform.source_file_relpath);
  const result: SourceResult = {
    source_file_relpath: transform.source_file_relpath,
    rows_present: false,
    rows_read: 0,
    rows_written: 0,
    rows_skipped: 0,
    rows_deduped: 0,
    output_files: [],
  };

  if (!existsSync(source_path)) return result;
  result.rows_present = true;

  const partition = ISO_DATE_PARTITION(opts.recorded_at);
  const stem = OUTPUT_STEM(transform.source_file_relpath);
  const out_dir = resolve(evidence_dir, partition);
  const out_path = resolve(out_dir, `${stem}.jsonl`);

  if (!opts.dry_run) mkdirSync(out_dir, { recursive: true });

  // Idempotency: collect sig_hashes already in the target output file
  // so we skip rows that were materialized in a prior run of the same
  // day. Tests pin this invariant.
  const seenHashes = loadSeenHashes(out_path);

  const lines = readFileSync(source_path, "utf8").split("\n");
  const rowsToWrite: string[] = [];
  const skipsToWrite: string[] = [];

  for (let i = 0; i < lines.length; i++) {
    const raw = lines[i];
    if (!raw) continue;
    result.rows_read++;

    let row: any;
    try { row = JSON.parse(raw); }
    catch (e) {
      result.rows_skipped++;
      skipsToWrite.push(JSON.stringify({
        source_file: transform.source_file_relpath,
        line_offset: i,
        errors: ["JSON.parse failed: " + (e as Error).message.slice(0, 200)],
        recorded_at: opts.recorded_at,
      }));
      continue;
    }

    const sig_hash = await canonicalSha256(row);
    if (seenHashes.has(sig_hash)) {
      result.rows_deduped++;
      continue;
    }
    seenHashes.add(sig_hash);

    const partial = transform.transform({
      row,
      line_offset: i,
      source_file_relpath: transform.source_file_relpath,
      recorded_at: opts.recorded_at,
      sig_hash,
    });
    if (!partial) {
      result.rows_skipped++;
      skipsToWrite.push(JSON.stringify({
        source_file: transform.source_file_relpath,
        line_offset: i,
        errors: ["transform returned null"],
        sig_hash,
        recorded_at: opts.recorded_at,
      }));
      continue;
    }

    const v = validateEvidenceRecord(partial);
    if (!v.valid) {
      result.rows_skipped++;
      skipsToWrite.push(JSON.stringify({
        source_file: transform.source_file_relpath,
        line_offset: i,
        errors: v.errors,
        sig_hash,
        recorded_at: opts.recorded_at,
      }));
      continue;
    }

    rowsToWrite.push(JSON.stringify(v.value));
    result.rows_written++;
  }

  if (!opts.dry_run) {
    if (rowsToWrite.length > 0) {
      const block = rowsToWrite.join("\n") + "\n";
      // Append-mode preserves prior runs' rows; dedup above ensures
      // we don't append duplicates of those.
      appendFileSync(out_path, block);
      result.output_files.push(out_path);
    }
    if (skipsToWrite.length > 0) {
      mkdirSync(dirname(skips_path), { recursive: true });
      appendFileSync(skips_path, skipsToWrite.join("\n") + "\n");
    }
  }

  return result;
}

export async function materializeAll(opts: MaterializeOptions): Promise<MaterializeResult> {
  const evidence_dir = resolve(opts.root, "data/evidence");
  const skips_path = resolve(opts.root, "data/_kb/distillation_skips.jsonl");
  const reports_dir = resolve(opts.root, "reports/distillation");

  const started_ms = Date.now();
  const sources: SourceResult[] = [];

  for (const t of opts.transforms) {
    sources.push(await processSource(t, opts, evidence_dir, skips_path));
  }

  const totals = sources.reduce(
    (acc, s) => ({
      rows_read: acc.rows_read + s.rows_read,
      rows_written: acc.rows_written + s.rows_written,
      rows_skipped: acc.rows_skipped + s.rows_skipped,
      rows_deduped: acc.rows_deduped + s.rows_deduped,
    }),
    { rows_read: 0, rows_written: 0, rows_skipped: 0, rows_deduped: 0 },
  );

  // Build the receipt — substantive per the spec non-negotiable.
  const ended_at = new Date().toISOString();
  const duration_ms = Date.now() - started_ms;

  const input_files: FileReference[] = [];
  for (const s of sources) {
    if (s.rows_present) {
      const path = resolve(opts.root, s.source_file_relpath);
      try {
        input_files.push({
          path: s.source_file_relpath,
          sha256: sha256OfFile(path),
          bytes: statSync(path).size,
        });
      } catch { /* file vanished mid-run — tally as missing in record_counts */ }
    }
  }

  const output_files: FileReference[] = [];
  for (const s of sources) {
    for (const path of s.output_files) {
      try {
        output_files.push({
          path: path.replace(opts.root + "/", ""),
          sha256: sha256OfFile(path),
          bytes: statSync(path).size,
        });
      } catch { /* not written in dry-run */ }
    }
  }

  const errors: string[] = [];
  const warnings: string[] = [];
  for (const s of sources) {
    if (!s.rows_present) warnings.push(`${s.source_file_relpath}: source file not found (skipped)`);
    if (s.rows_skipped > 0) warnings.push(`${s.source_file_relpath}: ${s.rows_skipped} rows skipped (validation/parse errors)`);
  }

  const receipt: Receipt = {
    schema_version: RECEIPT_SCHEMA_VERSION,
    command: "bun run scripts/distillation/build_evidence_index.ts" + (opts.dry_run ? " --dry-run" : ""),
    git_sha: getGitSha(opts.root),
    git_branch: getGitBranch(opts.root),
    git_dirty: getGitDirty(opts.root),
    started_at: opts.recorded_at,
    ended_at,
    duration_ms,
    input_files,
    output_files,
    record_counts: {
      in: totals.rows_read,
      out: totals.rows_written,
      skipped: totals.rows_skipped,
      deduped: totals.rows_deduped,
    },
    validation_pass: totals.rows_skipped === 0,
    errors,
    warnings,
  };

  // Self-validate the receipt — spec says receipts must conform to
  // their schema. Fail fast if our own writer drifts from the schema.
  const rv = validateReceipt(receipt);
  if (!rv.valid) {
    errors.push(...rv.errors.map(e => "receipt schema: " + e));
    receipt.errors = errors;
    receipt.validation_pass = false;
  }

  const stamp = ended_at.replace(/[:.]/g, "-");
  const receipt_dir = resolve(reports_dir, stamp);
  const receipt_path = resolve(receipt_dir, "receipt.json");
  if (!opts.dry_run) {
    mkdirSync(receipt_dir, { recursive: true });
    writeFileSync(receipt_path, JSON.stringify(receipt, null, 2) + "\n");
  }

  return { sources, totals, receipt, receipt_path, evidence_dir, skips_path };
}

async function cli() {
  const dry_run = process.argv.includes("--dry-run");
  const recorded_at = new Date().toISOString();
  const r = await materializeAll({
    root: DEFAULT_ROOT,
    transforms: TRANSFORMS,
    recorded_at,
    dry_run,
  });

  console.log(`[evidence_index] ${r.totals.rows_read} read · ${r.totals.rows_written} written · ${r.totals.rows_skipped} skipped · ${r.totals.rows_deduped} deduped${dry_run ? " (DRY RUN)" : ""}`);
  for (const s of r.sources) {
    if (!s.rows_present) {
      console.log(`  ${s.source_file_relpath}: (missing — skipped)`);
      continue;
    }
    console.log(`  ${s.source_file_relpath}: read=${s.rows_read} wrote=${s.rows_written} skip=${s.rows_skipped} dedup=${s.rows_deduped}`);
  }
  if (!dry_run) {
    console.log(`[evidence_index] receipt: ${r.receipt_path}`);
    console.log(`[evidence_index] validation_pass=${r.receipt.validation_pass}`);
  }
  if (!r.receipt.validation_pass) process.exit(1);
}

if (import.meta.main) {
  cli().catch(e => { console.error(e); process.exit(1); });
}