// ── Node.js test suite for pure functions ─────────────────────────────────
//
// Tests all pure (DOM-independent) utility functions used in the app.
// Run with: node tests/node/test-pure.js
//
// No external dependencies — uses only Node.js built-in assert.
//

const assert = require("assert");


// ═══════════════════════════════════════════════════════════════════════════
//  Helpers — extracted from helpers.js (pure functions only)
// ═══════════════════════════════════════════════════════════════════════════

function splitValueAndUnit(str, defaultNum) {
  const trimmed = (str || "").trim();
  const parts = trimmed.split(/\s+/);
  let numVal, unitSuffix;
  if (parts.length < 2 || isNaN(parseFloat(parts[0]))) {
    numVal = parseFloat(trimmed);
    unitSuffix = null;
  } else {
    numVal = parseFloat(parts[0]);
    unitSuffix = parts.slice(1).join(" ");
  }
  return { numVal: isNaN(numVal) ? defaultNum : numVal, unitSuffix };
}

function escapeString(str) {
  return str
    .replace(/\\/g, "\\\\").replace(/"/g, '\\"')
    .replace(/\n/g, "\\n").replace(/\r/g, "\\r").replace(/\t/g, "\\t")
    .replace(/\f/g, "\\f").replace(/\v/g, "\\v").replace(/\0/g, "\\0");
}

const C_KEYWORDS = new Set([
  "auto","break","case","char","const","continue","default","do","double",
  "else","enum","extern","float","for","goto","if","int","long","register",
  "return","short","signed","sizeof","static","struct","switch","typedef",
  "union","unsigned","void","volatile","while"
]);

function toCName(str) {
  let s = (str || "").trim().toLowerCase();
  s = s.replace(/[^a-z0-9_]/g, "_");
  s = s.replace(/_+/g, "_");
  s = s.replace(/^_|_$/g, "");
  if (/^\d/.test(s)) s = "_" + s;
  if (!s || C_KEYWORDS.has(s)) s = (s || "var") + "_";
  return s;
}

function deriveNaturalName(techName) {
  if (!techName) return "";
  let s = techName;
  s = s.replace(/^(SDL_|glfw|gl_?)/i, '');
  const known = {
    puts: "Print String",
    printf: "Print Formatted",
    getchar: "Get Char",
    putchar: "Put Char",
    perror: "Print Error",
    malloc: "Allocate Memory",
    atoi: "Parse Int",
    atof: "Parse Float",
    strlen: "String Length",
    strcmp: "Compare Strings",
    fabs: "Abs Float",
    fmod: "Float Modulo",
  };
  if (known[s]) return known[s];
  s = s.replace(/([a-z])([A-Z])/g, '$1 $2');
  s = s.replace(/_/g, ' ');
  s = s.replace(/([A-Z]+)([A-Z][a-z])/g, '$1 $2');
  s = s.replace(/\s+/g, ' ').trim();
  return s.charAt(0).toUpperCase() + s.slice(1);
}

function commentPrefix(naturalName, comment) {
  naturalName = (naturalName || "").trim();
  comment = (comment || "").trim();
  return comment && naturalName ? `// ${naturalName}: ${comment}\n` : comment ? `// ${comment}\n` : "";
}


// ═══════════════════════════════════════════════════════════════════════════
//  Format spec helpers — extracted from blocks-proc.js
// ═══════════════════════════════════════════════════════════════════════════

const _FMT_SPEC_RE = /%(?:[+\- #0]*\d*(?:\.\d+)?)([diufFeEgGxXoscpaAn%])/g;

function _specDataType(spec) {
  if ("di".includes(spec))   return "int";
  if ("u".includes(spec))    return "int";
  if ("fFeEgGaA".includes(spec)) return "double";
  if ("s".includes(spec))    return "string";
  return "int";
}

function _parseFormatSpecifiers(fmt) {
  const specs = [];
  let m;
  _FMT_SPEC_RE.lastIndex = 0;
  while ((m = _FMT_SPEC_RE.exec(fmt)) !== null) {
    if (m[1] === "%") continue;
    specs.push({ full: m[0], spec: m[1] });
  }
  return specs;
}


// ═══════════════════════════════════════════════════════════════════════════
//  Errno helpers — from blocks-algo.js
// ═══════════════════════════════════════════════════════════════════════════

const ERRNO_LIST = [
  { code: 1, name: "EPERM", desc: "Operation not permitted" },
  { code: 2, name: "ENOENT", desc: "No such file or directory" },
  { code: 3, name: "ESRCH", desc: "No such process" },
];

function _buildErrnoItems() {
  const items = [
    { code: 0,   name: "success",       desc: "success" },
    { code: 255, name: "error",         desc: "generic error" },
  ];
  for (const e of ERRNO_LIST) {
    items.push({ code: e.code, name: e.name, desc: e.desc });
  }
  return items;
}


// ═══════════════════════════════════════════════════════════════════════════
//  Geometry helpers — from sections.js
// ═══════════════════════════════════════════════════════════════════════════

function _shoelace(pts) {
  if (pts.length < 3) return 0;
  let s = 0;
  for (let i = 0; i < pts.length; i++) {
    const j = (i + 1) % pts.length;
    s += pts[i].x * pts[j].y - pts[j].x * pts[i].y;
  }
  return Math.abs(s) / 2;
}

function _ptInPoly(px, py, pts) {
  let inside = false;
  for (let i = 0, j = pts.length - 1; i < pts.length; j = i++) {
    const xi = pts[i].x, yi = pts[i].y, xj = pts[j].x, yj = pts[j].y;
    if ((yi > py) !== (yj > py) && px < (xj - xi) * (py - yi) / (yj - yi) + xi)
      inside = !inside;
  }
  return inside;
}

function _segmentsIntersect(a, b, c, d) {
  const det = (b.y - a.y) * (d.x - c.x) - (b.x - a.x) * (d.y - c.y);
  if (Math.abs(det) < 1) return false;
  const t = ((c.y - a.y) * (d.x - c.x) - (c.x - a.x) * (d.y - c.y)) / det;
  const u = ((b.x - a.x) * (c.y - a.y) - (b.y - a.y) * (c.x - a.x)) / det;
  return t >= 0 && t <= 1 && u >= 0 && u <= 1;
}

function _rectPolyOverlap(rx, ry, rw, rh, pts) {
  const corners = [
    { x: rx, y: ry }, { x: rx + rw, y: ry },
    { x: rx + rw, y: ry + rh }, { x: rx, y: ry + rh }
  ];
  for (let i = 0; i < pts.length; i++) {
    const j = (i + 1) % pts.length;
    for (const c of corners) {
      if (_segmentsIntersect(pts[i], pts[j], { x: rx, y: ry }, c)) return true;
    }
  }
  for (let i = 0; i < corners.length; i++) {
    const j = (i + 1) % corners.length;
    for (let k = 0; k < pts.length; k++) {
      const l = (k + 1) % pts.length;
      if (_segmentsIntersect(corners[i], corners[j], pts[k], pts[l])) return true;
    }
  }
  for (const c of corners) { if (_ptInPoly(c.x, c.y, pts)) return true; }
  for (const p of pts) { if (p.x >= rx && p.x <= rx + rw && p.y >= ry && p.y <= ry + rh) return true; }
  return false;
}


// ═══════════════════════════════════════════════════════════════════════════
//  Route helper — from draw.js
// ═══════════════════════════════════════════════════════════════════════════

function routeBetween(x1, y1, x2, y2) {
  const dx = x2 - x1, dy = y2 - y1;
  const adx = Math.abs(dx), ady = Math.abs(dy);
  if (adx === 0 && ady === 0) return `L ${x2} ${y2}`;
  const sx = dx >= 0 ? 1 : -1;
  const sy = dy >= 0 ? 1 : -1;
  const R45 = Math.PI / 4, R90 = Math.PI / 2, TOL = 5 * Math.PI / 180;
  const normAngle = (() => {
    const raw = Math.abs(Math.atan2(dy, dx));
    return raw > R90 ? Math.PI - raw : raw;
  })();
  if (
    Math.abs(normAngle) < TOL ||
    Math.abs(normAngle - R45) < TOL ||
    Math.abs(normAngle - R90) < TOL
  ) {
    return `L ${x2} ${y2}`;
  }
  if (adx >= ady) {
    const x1m = x1 + sx * ((adx - ady) / 2);
    const x2m = x1m + sx * ady;
    return `L ${x1m} ${y1} L ${x2m} ${y2} L ${x2} ${y2}`;
  } else {
    const y1m = y1 + sy * ((ady - adx) / 2);
    const y2m = y1m + sy * adx;
    return `L ${x1} ${y1m} L ${x2} ${y2m} L ${x2} ${y2}`;
  }
}


// ═══════════════════════════════════════════════════════════════════════════
//  Tests
// ═══════════════════════════════════════════════════════════════════════════

let passed = 0, failed = 0;

function test(name, fn) {
  try { fn(); passed++; }
  catch (e) { console.error(`FAIL: ${name}\n  ${e.message}`); failed++; }
}

function group(name, fn) {
  console.log(`\n── ${name} ──`);
  fn();
}


// ── splitValueAndUnit ─────────────────────────────────────────────────────

group("splitValueAndUnit", () => {
  test("parses number with unit", () => {
    const r = splitValueAndUnit("5 km", 0);
    assert.strictEqual(r.numVal, 5);
    assert.strictEqual(r.unitSuffix, "km");
  });

  test("parses number with multi-word unit", () => {
    const r = splitValueAndUnit("100 km/h", 0);
    assert.strictEqual(r.numVal, 100);
    assert.strictEqual(r.unitSuffix, "km/h");
  });

  test("parses bare number", () => {
    const r = splitValueAndUnit("42", 0);
    assert.strictEqual(r.numVal, 42);
    assert.strictEqual(r.unitSuffix, null);
  });

  test("returns default for NaN", () => {
    const r = splitValueAndUnit("abc", 10);
    assert.strictEqual(r.numVal, 10);
    assert.strictEqual(r.unitSuffix, null);
  });

  test("handles empty string", () => {
    const r = splitValueAndUnit("", 5);
    assert.strictEqual(r.numVal, 5);
    assert.strictEqual(r.unitSuffix, null);
  });

  test("parses negative number with unit", () => {
    const r = splitValueAndUnit("-3.5 m", 0);
    assert.strictEqual(r.numVal, -3.5);
    assert.strictEqual(r.unitSuffix, "m");
  });
});


// ── escapeString ──────────────────────────────────────────────────────────

group("escapeString", () => {
  test("escapes backslash", () => {
    assert.strictEqual(escapeString("a\\b"), "a\\\\b");
  });

  test("escapes double quote", () => {
    assert.strictEqual(escapeString('he"llo'), 'he\\"llo');
  });

  test("escapes newline", () => {
    assert.strictEqual(escapeString("a\nb"), "a\\nb");
  });

  test("escapes carriage return", () => {
    assert.strictEqual(escapeString("a\rb"), "a\\rb");
  });

  test("escapes tab", () => {
    assert.strictEqual(escapeString("a\tb"), "a\\tb");
  });

  test("escapes form feed", () => {
    assert.strictEqual(escapeString("a\fb"), "a\\fb");
  });

  test("escapes vertical tab", () => {
    assert.strictEqual(escapeString("a\vb"), "a\\vb");
  });

  test("escapes null byte", () => {
    assert.strictEqual(escapeString("a\0b"), "a\\0b");
  });

  test("passes through normal string", () => {
    assert.strictEqual(escapeString("hello world"), "hello world");
  });

  test("handles empty string", () => {
    assert.strictEqual(escapeString(""), "");
  });
});


// ── toCName ───────────────────────────────────────────────────────────────

group("toCName", () => {
  test("lowercases input", () => {
    assert.strictEqual(toCName("Hello"), "hello");
  });

  test("replaces spaces with underscores", () => {
    assert.strictEqual(toCName("my var"), "my_var");
  });

  test("replaces special chars with underscores", () => {
    assert.strictEqual(toCName("x@y#z"), "x_y_z");
  });

  test("collapses consecutive underscores", () => {
    assert.strictEqual(toCName("a___b"), "a_b");
  });

  test("strips leading/trailing underscores", () => {
    assert.strictEqual(toCName("_hello_"), "hello");
  });

  test("prepends underscore for leading digit", () => {
    assert.strictEqual(toCName("1var"), "_1var");
  });

  test("appends underscore for C keyword", () => {
    assert.strictEqual(toCName("int"), "int_");
    assert.strictEqual(toCName("return"), "return_");
    assert.strictEqual(toCName("while"), "while_");
  });

  test("handles empty input", () => {
    assert.strictEqual(toCName(""), "var_");
    assert.strictEqual(toCName(null), "var_");
    assert.strictEqual(toCName(undefined), "var_");
  });

  test("handles single char", () => {
    assert.strictEqual(toCName("x"), "x");
  });

  test("handles input with only special chars", () => {
    assert.strictEqual(toCName("@#$"), "var_");
  });
});


// ── deriveNaturalName ─────────────────────────────────────────────────────

group("deriveNaturalName", () => {
  test("strips SDL_ prefix", () => {
    assert.strictEqual(deriveNaturalName("SDL_CreateWindow"), "Create Window");
  });

  test("strips glfw prefix", () => {
    assert.strictEqual(deriveNaturalName("glfwInit"), "Init");
  });

  test("strips gl_ prefix", () => {
    assert.strictEqual(deriveNaturalName("glClear"), "Clear");
  });

  test("uses known name map", () => {
    assert.strictEqual(deriveNaturalName("puts"), "Print String");
    assert.strictEqual(deriveNaturalName("printf"), "Print Formatted");
    assert.strictEqual(deriveNaturalName("strlen"), "String Length");
  });

  test("converts snake_case", () => {
    assert.strictEqual(deriveNaturalName("my_func"), "My func");
  });

  test("returns empty for null/undefined", () => {
    assert.strictEqual(deriveNaturalName(null), "");
    assert.strictEqual(deriveNaturalName(undefined), "");
    assert.strictEqual(deriveNaturalName(""), "");
  });
});


// ── commentPrefix ─────────────────────────────────────────────────────────

group("commentPrefix", () => {
  test("generates full prefix with name and comment", () => {
    assert.strictEqual(
      commentPrefix("My Flag", "indicates status"),
      "// My Flag: indicates status\n"
    );
  });

  test("generates comment-only prefix", () => {
    assert.strictEqual(commentPrefix("", "just a note"), "// just a note\n");
  });

  test("returns empty when no comment", () => {
    assert.strictEqual(commentPrefix("My Flag", ""), "");
  });

  test("returns empty when both empty", () => {
    assert.strictEqual(commentPrefix("", ""), "");
  });

  test("trims whitespace", () => {
    assert.strictEqual(
      commentPrefix("  name  ", "  desc  "),
      "// name: desc\n"
    );
  });
});


// ── _specDataType & _parseFormatSpecifiers ────────────────────────────────

group("Format specifiers", () => {
  test("_specDataType maps d/i to int", () => {
    assert.strictEqual(_specDataType("d"), "int");
    assert.strictEqual(_specDataType("i"), "int");
  });

  test("_specDataType maps u to int", () => {
    assert.strictEqual(_specDataType("u"), "int");
  });

  test("_specDataType maps fFeEgGaA to double", () => {
    for (const c of "fFeEgGaA") {
      assert.strictEqual(_specDataType(c), "double", `char: ${c}`);
    }
  });

  test("_specDataType maps s to string", () => {
    assert.strictEqual(_specDataType("s"), "string");
  });

  test("_specDataType defaults to int for unknown", () => {
    assert.strictEqual(_specDataType("n"), "int");
  });

  test("_parseFormatSpecifiers finds %d, %f, %s", () => {
    const r = _parseFormatSpecifiers("x=%d y=%f name=%s");
    assert.strictEqual(r.length, 3);
    assert.strictEqual(r[0].spec, "d");
    assert.strictEqual(r[1].spec, "f");
    assert.strictEqual(r[2].spec, "s");
  });

  test("_parseFormatSpecifiers handles width and precision", () => {
    const r = _parseFormatSpecifiers("x=%10.2f");
    assert.strictEqual(r.length, 1);
    assert.strictEqual(r[0].spec, "f");
    assert.strictEqual(r[0].full, "%10.2f");
  });

  test("_parseFormatSpecifiers handles %% (escaped percent)", () => {
    const r = _parseFormatSpecifiers("50%% %d");
    assert.strictEqual(r.length, 1);
    assert.strictEqual(r[0].spec, "d");
  });

  test("_parseFormatSpecifiers returns empty for no matches", () => {
    assert.deepStrictEqual(_parseFormatSpecifiers("hello"), []);
    assert.deepStrictEqual(_parseFormatSpecifiers(""), []);
  });
});


// ── _buildErrnoItems ──────────────────────────────────────────────────────

group("_buildErrnoItems", () => {
  const items = _buildErrnoItems();

  test("includes success (code 0) first", () => {
    assert.strictEqual(items[0].code, 0);
    assert.strictEqual(items[0].name, "success");
  });

  test("includes generic error (code 255) second", () => {
    assert.strictEqual(items[1].code, 255);
    assert.strictEqual(items[1].name, "error");
  });

  test("includes ERRNO_LIST items after defaults", () => {
    assert.ok(items.length > 2);
    assert.strictEqual(items[2].name, "EPERM");
  });
});


// ── routeBetween ──────────────────────────────────────────────────────────

group("routeBetween", () => {
  test("returns direct line for zero distance", () => {
    assert.strictEqual(routeBetween(10, 10, 10, 10), "L 10 10");
  });

  test("returns direct line for horizontal move", () => {
    const r = routeBetween(0, 0, 100, 0);
    assert.strictEqual(r, "L 100 0");
  });

  test("returns direct line for vertical move", () => {
    const r = routeBetween(0, 0, 0, 100);
    assert.strictEqual(r, "L 0 100");
  });

  test("returns direct line for 45-degree move", () => {
    const r = routeBetween(0, 0, 100, 100);
    assert.strictEqual(r, "L 100 100");
  });

  test("routes 3-segment for non-45-degree move (wider than tall)", () => {
    const r = routeBetween(0, 0, 200, 50);
    assert.strictEqual(r, "L 75 0 L 125 50 L 200 50");
  });

  test("routes 3-segment for non-45-degree move (taller than wide)", () => {
    const r = routeBetween(0, 0, 50, 200);
    assert.strictEqual(r, "L 0 75 L 50 125 L 50 200");
  });
});


// ── _shoelace (polygon area) ──────────────────────────────────────────────

group("_shoelace", () => {
  test("returns 0 for empty array", () => {
    assert.strictEqual(_shoelace([]), 0);
  });

  test("returns 0 for less than 3 points", () => {
    assert.strictEqual(_shoelace([{x:0,y:0},{x:1,y:0}]), 0);
  });

  test("computes area of a 10x10 square", () => {
    const pts = [{x:0,y:0},{x:10,y:0},{x:10,y:10},{x:0,y:10}];
    assert.strictEqual(_shoelace(pts), 100);
  });

  test("computes area of a right triangle (3-4-5)", () => {
    const pts = [{x:0,y:0},{x:3,y:0},{x:0,y:4}];
    assert.strictEqual(_shoelace(pts), 6);
  });

  test("handles negative coordinates", () => {
    const pts = [{x:-5,y:-5},{x:5,y:-5},{x:5,y:5},{x:-5,y:5}];
    assert.strictEqual(_shoelace(pts), 100);
  });
});


// ── _ptInPoly (point in polygon) ──────────────────────────────────────────

group("_ptInPoly", () => {
  const sq = [{x:0,y:0},{x:10,y:0},{x:10,y:10},{x:0,y:10}];

  test("returns true for point inside square", () => {
    assert.ok(_ptInPoly(5, 5, sq));
  });

  test("returns false for point outside square (left)", () => {
    assert.ok(!_ptInPoly(-1, 5, sq));
  });

  test("returns false for point outside square (above)", () => {
    assert.ok(!_ptInPoly(5, -1, sq));
  });

  test("returns true for point on edge (boundary)", () => {
    assert.ok(_ptInPoly(0, 5, sq));
  });

  test("handles concave L-shaped polygon", () => {
    const L = [{x:0,y:0},{x:8,y:0},{x:8,y:3},{x:3,y:3},{x:3,y:8},{x:0,y:8}];
    assert.ok(_ptInPoly(1, 1, L));        // inside L
    assert.ok(!_ptInPoly(5, 5, L));       // in the notch
    assert.ok(_ptInPoly(1, 5, L));        // inside, left arm
    assert.ok(!_ptInPoly(-1, 5, L));      // outside, left of shape
  });
});


// ── _segmentsIntersect ────────────────────────────────────────────────────

group("_segmentsIntersect", () => {
  test("returns true for crossing segments", () => {
    assert.ok(_segmentsIntersect({x:0,y:0},{x:10,y:10},{x:0,y:10},{x:10,y:0}));
  });

  test("returns false for parallel non-crossing segments", () => {
    assert.ok(!_segmentsIntersect({x:0,y:0},{x:10,y:0},{x:0,y:10},{x:10,y:10}));
  });

  test("returns false for collinear non-overlapping segments", () => {
    assert.ok(!_segmentsIntersect({x:0,y:0},{x:5,y:5},{x:6,y:6},{x:10,y:10}));
  });

  test("returns true when sharing endpoint", () => {
    assert.ok(_segmentsIntersect({x:0,y:0},{x:5,y:5},{x:5,y:5},{x:10,y:0}));
  });

  test("returns false for disjoint segments", () => {
    assert.ok(!_segmentsIntersect({x:0,y:0},{x:2,y:2},{x:8,y:8},{x:10,y:10}));
  });
});


// ── _rectPolyOverlap (rectangle vs polygon) ───────────────────────────────

group("_rectPolyOverlap", () => {
  const tri = [{x:0,y:0},{x:10,y:0},{x:5,y:10}];

  test("returns true when rect overlaps polygon", () => {
    assert.ok(_rectPolyOverlap(4, 2, 2, 2, tri));
  });

  test("returns false when rect is far from polygon", () => {
    assert.ok(!_rectPolyOverlap(50, 50, 5, 5, tri));
  });

  test("returns true when rect contains a polygon vertex", () => {
    assert.ok(_rectPolyOverlap(8, -2, 5, 5, tri));
  });

  test("returns true when polygon encloses a rect corner", () => {
    assert.ok(_rectPolyOverlap(4, 1, 1, 1, tri));
  });

  test("returns false for rect outside with zero-size", () => {
    assert.ok(!_rectPolyOverlap(100, 100, 0, 0, tri));
  });
});


// ═══════════════════════════════════════════════════════════════════════════
//  Report
// ═══════════════════════════════════════════════════════════════════════════

console.log(`\n${"=".repeat(50)}`);
const total = passed + failed;
console.log(`Results: ${passed}/${total} passed`);
if (failed > 0) {
  console.log(`FAILURES: ${failed} test(s) failed`);
  process.exit(1);
} else {
  console.log("All tests passed.");
}