#!/usr/bin/env node
/*
 * build-mini-graph.mjs — builds the committed mini-graph.bin fixture.
 * ----------------------------------------------------------------------
 * A MAINTAINER-TIME REPO TOOL: regenerates routing/test/fixtures/
 * mini-graph.bin — the A* correctness ground truth (plan 06-01) and the
 * snap/astar suites' shared fixture. NOT a runtime dependency; nothing in
 * bot/src/, web/src/, or routing/src/ imports it. Tests consume the
 * COMMITTED binary; only a deliberate fixture redesign re-runs this.
 *
 * PROVENANCE (Phase 8 plan 08-01): routing/test/fixtures/mini-graph-arg1.bin
 * holds the frozen ARG1-era bytes preserved expressly as the v1
 * decode-rejection vector consumed by the G-suite — it is NOT regenerated
 * by this script, ever.
 *
 * Usage:   node routing/test/fixtures/build-mini-graph.mjs
 * Exit:    0 on write; throws on any invariant violation (never writes).
 *
 * ARG2 (plan 08-02): the fixture carries a tiny real landmark stage —
 * L=2 anchors via farthestPointAnchors + quantized c-metric tables via
 * landmarkTables (the SAME pure module the real build script uses), passed
 * through the ONE encodeGraph authority. Deterministic: identical output
 * bytes on every re-run.
 *
 * Design (pinned by 06-01): a hand-built 5x5 grid in a ~0.002 deg x 0.002 deg
 * bbox near KL center (lat 3.1500–3.1520, lng 101.6900–101.6920):
 *   - 25 nodes, 80 directed edge entries (20 H + 20 V segments, both ways)
 *   - three named streets: "Jalan Mini 1" (interior E-W rows),
 *     "Jalan Mini 2" (interior N-S columns), "Jalan Persiaran Mini" (perimeter)
 *   - exactly ONE oneway pair: 2 -> 3 traversable, 3 -> 2 flagged bit0
 *   - two speed classes: perimeter 60 km/h, interior 30 km/h
 *     (weights = segment meters / (kmh / 3.6), meters via haversineM)
 */
import { writeFileSync } from "node:fs";
import { encodeGraph } from "../../src/graph.ts";
import { haversineM } from "../../src/geo.ts";
import { LANDMARK_QUANTUM_S, farthestPointAnchors, landmarkTables, landmarkCoverage } from "../../src/landmark.ts";

const GRID = 5;
const LAT0 = 3.15;
const LNG0 = 101.69;
const STEP_DEG = 0.0005;
/** The single oneway pair (grid ids: row 0, cols 2->3). */
const ONEWAY_U = 2;
const ONEWAY_V = 3;

const NAME_MINI_1 = 0; // interior E-W rows
const NAME_MINI_2 = 1; // interior N-S columns
const NAME_PERIMETER = 2;
const names = ["Jalan Mini 1", "Jalan Mini 2", "Jalan Persiaran Mini"];

const SPEED_PERIMETER_KMH = 60;
const SPEED_INTERIOR_KMH = 30;

const lat = [];
const lng = [];
for (let r = 0; r < GRID; r++) {
  for (let c = 0; c < GRID; c++) {
    // 1e-6 integer grid then divide — exact decimal coordinates (the codec's
    // grid law); naive `3.15 + r * 0.0005` accumulates float error.
    lat.push((3150000 + r * 500) / 1e6);
    lng.push((101690000 + c * 500) / 1e6);
  }
}
const id = (r, c) => r * GRID + c;

const edges = [];
function addEdge(u, v, nameId) {
  const kmh = nameId === NAME_PERIMETER ? SPEED_PERIMETER_KMH : SPEED_INTERIOR_KMH;
  const meters = haversineM({ lat: lat[u], lng: lng[u] }, { lat: lat[v], lng: lng[v] });
  edges.push({ from: u, to: v, seconds: meters / (kmh / 3.6), nameId });
}
for (let r = 0; r < GRID; r++) {
  for (let c = 0; c < GRID - 1; c++) {
    const nameId = r === 0 || r === GRID - 1 ? NAME_PERIMETER : NAME_MINI_1;
    addEdge(id(r, c), id(r, c + 1), nameId);
    addEdge(id(r, c + 1), id(r, c), nameId);
  }
}
for (let c = 0; c < GRID; c++) {
  for (let r = 0; r < GRID - 1; r++) {
    const nameId = c === 0 || c === GRID - 1 ? NAME_PERIMETER : NAME_MINI_2;
    addEdge(id(r, c), id(r + 1, c), nameId);
    addEdge(id(r + 1, c), id(r, c), nameId);
  }
}

// Exactly ONE oneway: the reverse mirror of U->V carries flags bit0.
const reverse = edges.find((e) => e.from === ONEWAY_V && e.to === ONEWAY_U);
if (!reverse) throw new Error("oneway reverse edge not found — grid invariant broken");
reverse.flags = 1;

if (edges.length !== 80) throw new Error(`expected 80 directed edges, built ${edges.length}`);

// LANDMARK STAGE (plan 08-02): the fixture regenerates as ARG2 THROUGH the
// one encode authority — the same farthestPointAnchors + landmarkTables the
// real build script (08-04) will run, at a tiny L. Fail-loud invariants
// before any write (the `edges.length !== 80` style).
const LANDMARK_COUNT = 2; // tiny L: the 5x5 grid needs exactly 2 well-spread anchors
const landmarkInput = { nodeCount: GRID * GRID, edges, quantumS: LANDMARK_QUANTUM_S };
const anchors = farthestPointAnchors(landmarkInput, LANDMARK_COUNT);
const { to, from } = landmarkTables(landmarkInput, anchors);
if (anchors.length !== LANDMARK_COUNT) throw new Error(`expected ${LANDMARK_COUNT} anchors, got ${anchors.length}`);
if (to.length !== LANDMARK_COUNT * GRID * GRID || from.length !== LANDMARK_COUNT * GRID * GRID) {
  throw new Error("landmark tables are not L*N row-major");
}
for (let l = 0; l < anchors.length; l++) {
  const a = anchors[l];
  if (to[l * GRID * GRID + a] !== 0 || from[l * GRID * GRID + a] !== 0) {
    throw new Error(`anchor ${l} (node ${a}) own cells are not 0 — table law broken`);
  }
}
const coverage = landmarkCoverage(to, anchors, GRID * GRID);
if (coverage.some((c) => c !== 1)) {
  throw new Error(`the grid is strongly connected — coverage must be 1.0, got ${coverage.join(", ")}`);
}

const bin = encodeGraph({
  lat,
  lng,
  edges,
  names,
  maxSpeedKmh: SPEED_PERIMETER_KMH,
  landmarks: { quantumS: LANDMARK_QUANTUM_S, nodes: anchors, to, from },
});
writeFileSync(new URL("./mini-graph.bin", import.meta.url), Buffer.from(bin));
console.log(
  `mini-graph.bin: ${GRID * GRID} nodes, ${edges.length} edges, 3 names, ` +
    `L=${LANDMARK_COUNT} landmarks (nodes ${[...anchors].join(",")}), quantum ${LANDMARK_QUANTUM_S}s, ` +
    `coverage ${coverage.map((c) => c.toFixed(2)).join("/")}, ${bin.byteLength} B`,
);