import { hookLength, NOMINAL_DIAMETER, type BarSize } from './common';
import { DEFAULT_FOOTING_REBAR, type FootingGridKey, type FootingRebarSettings } from './footing-settings';

/**
 * 확대기초 철근 B1–B8, B10–B12 (plan C5). Source: RAG/확대기초철근 (1).md, 2026-10-22 최종 정리.
 * B9 (전단철근) is not computed yet. Lengths in mm, heights in mm from the 확대기초 하면.
 */
/** 확대기초 고정 규칙 (사양): Δ₂ 하면 1·2단 간격 = 100 (고정). The other values are the editable defaults. */
export const DELTA2 = 100;

/** Kept for reference; the calculations read the settings passed in (승인 2026-10-26). */
export const FOOTING_DEFAULTS = { ...DEFAULT_FOOTING_REBAR, delta2: DELTA2 } as const;

export interface GridResult {
  /** 격자 칸 수 n = floor((A − 2·e_min)/s); 위치 수 = n + 1. */
  n: number;
  /** 격자 길이 G = n·s. */
  G: number;
  /** 양끝 여유 e = (A − G)/2. */
  e: number;
  /** 위치 수 n + 1. */
  positions: number;
}

/** Grid along one side of the footing (§3.1). side = W for B1–B4, L for B5–B8. */
export function grid(side: number, f: FootingRebarSettings = DEFAULT_FOOTING_REBAR, key: FootingGridKey = 'sAxis'): GridResult {
  const s = f[key];
  const A = side - 2 * f.cSide;
  const n = Math.floor((A - 2 * f.eMin) / s);
  const G = n * s;
  const e = (A - G) / 2;
  return { n, G, e, positions: n + 1 };
}

const d = (size: BarSize) => NOMINAL_DIAMETER[size];

/** Leg of B1·B3·B5·B7: 12·d_b on each end (proposed rule, spec §1.2 · Q-B5). */
export const legLength = (size: BarSize) => 12 * d(size);

/** Layer heights (§4.2), mm from the 하면. H = footing height. */
export interface Layers {
  B5: number;
  B1: number;
  B24: number;
  B68: number;
  B3: number;
  B7: number;
}

export function layers(H: number, f: FootingRebarSettings = DEFAULT_FOOTING_REBAR): Layers {
  const zB5 = H - f.cTop;
  const zB1 = zB5 - (d('S29') + d('S25')) / 2;
  const zB24 = f.cBottom;
  const zB68 = f.cBottom + (d('S25') + d('S29')) / 2;
  return { B5: zB5, B1: zB1, B24: zB24, B68: zB68, B3: zB24 + DELTA2, B7: zB68 + DELTA2 };
}

/** Lengths of the B1–B4 family along the length L (§5.2). */
export function legB2(H: number, f: FootingRebarSettings = DEFAULT_FOOTING_REBAR): number {
  const z = layers(H, f);
  return z.B1 - z.B24; // 1723 at H 2000
}

export interface FootingBar {
  name: 'B1' | 'B2' | 'B3' | 'B4' | 'B5' | 'B6' | 'B7' | 'B8' | 'B10-1' | 'B10-2' | 'B11' | 'B12';
  size: BarSize;
  /** Bars in all (over the footing). */
  count: number;
  /** Length of one bar, mm (straight part + legs). */
  length: number;
}

/** B1–B4 (§5): the grid along W, with lengths from L. */
export function bottomBars(L: number, W: number, H: number, f: FootingRebarSettings = DEFAULT_FOOTING_REBAR): FootingBar[] {
  const g = grid(W, f);
  const n = g.positions;
  const N4 = Math.ceil(n / 2); // B4 at even i
  const N2 = Math.floor(n / 2); // B2 at odd i
  const l0 = L - 2 * f.cSide;
  const leg2 = legB2(H, f);
  return [
    { name: 'B1', size: 'S25', count: N2, length: l0 + 2 * legLength('S25') },
    { name: 'B2', size: 'S25', count: N2, length: l0 + 2 * leg2 },
    { name: 'B3', size: 'S19', count: N2, length: l0 + 2 * legLength('S19') },
    { name: 'B4', size: 'S25', count: N4, length: l0 },
  ];
}

/** B5–B8 (§6): the grid along L, with lengths from W. */
export function crossBars(L: number, W: number, H: number, f: FootingRebarSettings = DEFAULT_FOOTING_REBAR): FootingBar[] {
  const g = grid(L, f, 'sPerp');
  const n = g.positions;
  const N8 = Math.ceil(n / 2); // B8 at even i
  const N6 = Math.floor(n / 2); // B6, B5, B7 at odd i
  const l0 = W - 2 * f.cSide;
  const z = layers(H, f);
  const leg6 = z.B5 - z.B68;
  return [
    { name: 'B5', size: 'S29', count: N6, length: l0 + 2 * legLength('S29') },
    { name: 'B6', size: 'S29', count: N6, length: l0 + 2 * leg6 },
    { name: 'B7', size: 'S19', count: N6, length: l0 + 2 * legLength('S19') },
    { name: 'B8', size: 'S29', count: N8, length: l0 },
  ];
}

/** B10 levels: m = floor((z_B5 − e_top − c_b)/s_v) (§7.1), so the count is m + 1 (9 for P1, H 2000). */
export function b10Levels(H: number, f: FootingRebarSettings = DEFAULT_FOOTING_REBAR): number {
  const m = Math.floor((layers(H, f).B5 - f.eTop - f.cBottom) / f.sV);
  return m + 1;
}

/** Depth of a side bar from the side face: c_s + (d_a + d_b)/2 (§7, §8.3). B10-1 hangs on B6, B10-2 on B2. */
export const sideDepth = (dOuter: number, dB10: number, f: FootingRebarSettings = DEFAULT_FOOTING_REBAR) => f.cSide + (dOuter + dB10) / 2;

/** B10-1 (on W sides) and B10-2 (on L sides): m + 1 levels at s_v, two faces each (§7). */
export function sideBars(L: number, W: number, H: number, f: FootingRebarSettings = DEFAULT_FOOTING_REBAR): FootingBar[] {
  const depth1 = sideDepth(NOMINAL_DIAMETER.S29, NOMINAL_DIAMETER.S19, f); // B10-1: 123.85
  const depth2 = sideDepth(NOMINAL_DIAMETER.S25, NOMINAL_DIAMETER.S19, f); // B10-2: 122.25
  const levels = b10Levels(H, f);
  const hook = hookLength('main90', d('S19'));
  return [
    { name: 'B10-1', size: 'S19', count: levels * 2, length: L - 2 * depth2 + 2 * hook },
    { name: 'B10-2', size: 'S19', count: levels * 2, length: W - 2 * depth1 + 2 * hook },
  ];
}

/** Assembly levels j = n, 2n, … strictly inside the B10 levels, 0 < j < m (§8.1). */
export function assemblyJs(H: number, f: FootingRebarSettings = DEFAULT_FOOTING_REBAR): number[] {
  const m = b10Levels(H, f) - 1;
  const js: number[] = [];
  for (let j = f.n; j < m; j += f.n) js.push(j);
  return js;
}

/** Ends of B11 / B12 lie (d_B10 + d_assembly)/2 further inside than the B10 depth, so the two bars just touch (§8.3). */
export function assemblyEndOffset(): number {
  return (d('S19') + d('S16')) / 2; // 17.5
}

/** B11 (along W, between the B10-2 levels) and B12 (along L), 4s apart with a 2s stagger per level (§8). */
/**
 * First grid index of the even group of the assembly bars (B11 or B12), chosen on EVEN indices (확대기초철근 (1).md §9.1: the
 * B5·B1 and B9 positions take the odd grid, so B11·B12 sit on the even grid and never overlap them). Among the even choices,
 * the one that centres the union of both 2-step-staggered groups best (left and right gaps as equal as possible) is used.
 */
export function assemblyEvenStart(n: number, k: number): number {
  let best = 0;
  let bestGap = Infinity;
  for (let e0 = 0; e0 + 2 <= n; e0 += 2) {
    const idx: number[] = [];
    for (const s of [e0, e0 + 2]) for (let i = s; i <= n; i += k) idx.push(i);
    const gap = Math.abs(Math.min(...idx) - (n - Math.max(...idx)));
    if (gap < bestGap) {
      best = e0;
      bestGap = gap;
    }
  }
  return best;
}

/**
 * Grid indices of the assembly bars (B11 or B12) on one level (승인 2026-10-26): every k grid steps, on even indices, with the
 * 2-step stagger between levels (even levels at e0, odd levels at e0 + 2). n = positions − 1; idx = level index (0, 1, …).
 */
export function assemblyGridIndices(n: number, k: number, idx: number): number[] {
  const start = idx % 2 === 0 ? assemblyEvenStart(n, k) : assemblyEvenStart(n, k) + 2;
  const count = start <= n ? Math.floor((n - start) / k) + 1 : 0;
  return Array.from({ length: count }, (_, m) => start + m * k);
}

export function assemblyBars(L: number, W: number, H: number, f: FootingRebarSettings = DEFAULT_FOOTING_REBAR): FootingBar[] {
  const levelsJ = assemblyJs(H, f);
  // B11 is spread along L (교각축 직각 grid) and B12 along W (교각축 grid), per 확대기초철근 (1).md §8.
  const nW = grid(W, f, 'sAxis').positions - 1;
  const nL = grid(L, f, 'sPerp').positions - 1;
  const b11 = levelsJ.reduce((a, _, idx) => a + assemblyGridIndices(nL, f.kB11, idx).length, 0);
  const b12 = levelsJ.reduce((a, _, idx) => a + assemblyGridIndices(nW, f.kB12, idx).length, 0);
  const hook = Math.round(hookLength('main90', d('S16'))); // 246 mm, rounded as in the document (§8.3)
  const depth1 = sideDepth(NOMINAL_DIAMETER.S29, NOMINAL_DIAMETER.S19, f);
  const depth2 = sideDepth(NOMINAL_DIAMETER.S25, NOMINAL_DIAMETER.S19, f);
  return [
    { name: 'B11', size: 'S16', count: b11, length: W - 2 * (depth1 + assemblyEndOffset()) + 2 * hook },
    { name: 'B12', size: 'S16', count: b12, length: L - 2 * (depth2 + assemblyEndOffset()) + 2 * hook },
  ];
}

/** Plane positions of the grid along one side, mm from the footing centre: x_i = −side/2 + c_s + e + i·s (§3.1). */
export function gridPositions(side: number, f: FootingRebarSettings = DEFAULT_FOOTING_REBAR, key: FootingGridKey = 'sAxis'): number[] {
  const g = grid(side, f, key);
  return Array.from({ length: g.positions }, (_, i) => -side / 2 + f.cSide + g.e + i * f[key]);
}

/** B9 bar of the rule (§9.1, Q-B18): a vertical bar at (x, n), mm from the footing centre. */
export interface B9Bar {
  x: number;
  n: number;
}

/**
 * B9 positions (확대기초철근 (1).md §9.1, rule applied): rows at W index 1, 5, 9 … (step 4 on the grid); in row r the L index
 * starts at 1 (even r) or 3 (odd r) and steps by 4. A bar is left out when it falls in a column zone: its centre is closer
 * than the column radius plus half a bar to a column axis (Q-B20, applied: the 기둥 구역 is removed).
 */
export function b9Bars(L: number, W: number, columnX: number[], columnD: number = 2000, f: FootingRebarSettings = DEFAULT_FOOTING_REBAR): { rows: number; perRow: number[]; bars: B9Bar[] } {
  const xs = gridPositions(L, f);
  const ns = gridPositions(W, f);
  const rowIndices: number[] = [];
  for (let i = 1; i < ns.length; i += 4) rowIndices.push(i);
  const halfBar = NOMINAL_DIAMETER.H16 / 2;
  const bars: B9Bar[] = [];
  const perRow = rowIndices.map((iW, r) => {
    const start = r % 2 === 0 ? 1 : 3;
    let kept = 0;
    for (let iL = start; iL < xs.length; iL += 4) {
      const x = xs[iL];
      const n = ns[iW];
      if (columnX.some((cx) => Math.hypot(x - cx, n) < columnD / 2 + halfBar)) continue;
      bars.push({ x, n });
      kept++;
    }
    return kept;
  });
  return { rows: rowIndices.length, perRow, bars };
}

/**
 * B9 전단철근 (확대기초철근 (1).md §9). Vertical bars from the B2·B4 level to the B5 level, H16, with 135° hooks at both ends.
 * Length = l_v + 2·l_h (l_v = z_B5 − z_B24). The hook tail (6·d) turns toward the footing centre (Q-B19, applied).
 */
export function shearB9(L: number, W: number, H: number, columnX: number[] = [], columnD: number = 2000, f: FootingRebarSettings = DEFAULT_FOOTING_REBAR): { rows: number; perRow: number[]; count: number; length: number; bars: B9Bar[] } {
  const { rows, perRow, bars } = b9Bars(L, W, columnX, columnD, f);
  const lv = layers(H, f).B5 - layers(H, f).B24; // 1750
  const lh = hookLength('stirrup135', d('H16'));
  return { rows, perRow, count: bars.length, length: lv + 2 * lh, bars };
}

/** Leg offsets from the grid line (§5.3, §6.3): the B1/B3 and B5/B7 legs sit beside the outer leg. */
export function legOffsets(): { B1: number; B3: number; B5: number; B7: number } {
  const dB2 = NOMINAL_DIAMETER.S25;
  const dB1 = NOMINAL_DIAMETER.S25;
  const dB3 = NOMINAL_DIAMETER.S19;
  const dB6 = NOMINAL_DIAMETER.S29;
  const dB5 = NOMINAL_DIAMETER.S29;
  const dB7 = NOMINAL_DIAMETER.S19;
  return {
    B1: (dB2 + dB1) / 2,
    B3: (dB2 + dB3) / 2,
    B5: (dB6 + dB5) / 2,
    B7: (dB6 + dB7) / 2,
  };
}

/** B11/B12 heights (§8.1): B10 levels at 150 + k·s_v; the assembly levels are j = n, 2n, 3n (n = 2), and B12 sits d_B10 above B11. */
export function assemblyHeights(H: number, f: FootingRebarSettings = DEFAULT_FOOTING_REBAR): { B11: number[]; B12: number[] } {
  const js = assemblyJs(H, f);
  const B11 = js.map((j) => f.cBottom + j * f.sV);
  const B12 = B11.map((z) => z + NOMINAL_DIAMETER.S19);
  return { B11, B12 };
}

/**
 * Values shown on the 확대기초 panel as rules and derived values (승인 2026-10-26). Each is read from the same functions the
 * rebar table and the 3D view use, so the panel cannot drift from the calculation. H is the footing height (mm).
 */
export function footingRuleValues(H: number, f: FootingRebarSettings = DEFAULT_FOOTING_REBAR): {
  upper2sAxis: number;
  upper2sPerp: number;
  delta2: number;
  b2Leg: number;
  b6Leg: number;
  b9Pitch: number;
  b9Stagger: number;
  b11Pitch: number;
  b12Pitch: number;
  assemblyVertical: number;
  assemblyLevels: number;
} {
  const z = layers(H, f);
  return {
    upper2sAxis: 2 * f.sAxis,
    upper2sPerp: 2 * f.sPerp,
    delta2: DELTA2,
    b2Leg: legB2(H, f),
    b6Leg: z.B5 - z.B68,
    b9Pitch: 4 * f.sAxis,
    b9Stagger: 2 * f.sAxis,
    b11Pitch: f.kB11 * f.sPerp,
    b12Pitch: f.kB12 * f.sAxis,
    assemblyVertical: f.n * f.sV,
    assemblyLevels: assemblyJs(H, f).length,
  };
}