import type { PierModel } from '../geometry';

/**
 * 받침블럭 철근 (spec §6.3 · plan C2), 배치 분리: one block per bearing, 1200 × 1200.
 * S2 is the upper bar (cover 50 from the block top); S1 is the lower bar (69.1 below the top).
 * Both have the same layout: 7@125 = 875 with ends of 162.5 in a 1200 mm block, and legs of 700 below the bar.
 */
export const BLOCK_REBAR = {
  dim: 1200,
  cover: 50,
  firstBarGap: 75,
  spacing: 125,
  /** Straight part of the bar for the 1200 block (spec table: 1100 + 700 × 2). */
  straight: 1100,
  legLength: 700,
  /** Depth of each bar centre below the block top (mm). */
  depthS2: 50,
  depthS1: 69.1,
} as const;

export interface BarRow {
  name: 'S1' | 'S2';
  /** Bars along one block side. */
  count: number;
  spacing: number;
  /** Position of the first bar from the block edge. */
  firstEnd: number;
  /** Straight length plus two legs (mm). */
  length: number;
  /** Coping embedment of the legs (mm): 700 − (block height − bar depth). */
  embedment: number;
}

/** Bars along one 1200 mm side: available = dim − 2·(cover + first gap); gaps = floor(available / spacing). */
export function barsAcross(dim: number = BLOCK_REBAR.dim): { count: number; spacing: number; firstEnd: number } {
  const available = dim - 2 * (BLOCK_REBAR.cover + BLOCK_REBAR.firstBarGap);
  const gaps = Math.floor(available / BLOCK_REBAR.spacing);
  const span = gaps * BLOCK_REBAR.spacing;
  const leftover = available - span;
  return { count: gaps + 1, spacing: BLOCK_REBAR.spacing, firstEnd: BLOCK_REBAR.cover + BLOCK_REBAR.firstBarGap + leftover / 2 };
}

/** Rebar of one block; blockHeight is the bearing block height in mm (h1 front or h2 back, pad included). */
export function blockBars(blockHeight: number, dim: number = BLOCK_REBAR.dim): BarRow[] {
  const across = barsAcross(dim);
  const length = BLOCK_REBAR.straight + 2 * BLOCK_REBAR.legLength;
  return [
    { name: 'S1', ...across, length, embedment: BLOCK_REBAR.legLength - (blockHeight - BLOCK_REBAR.depthS1) },
    { name: 'S2', ...across, length, embedment: BLOCK_REBAR.legLength - (blockHeight - BLOCK_REBAR.depthS2) },
  ];
}

export interface BlockRebar {
  no: number;
  row: '전열' | '후열';
  bars: BarRow[];
}

/** Rebar of every block of a pier, using the model's block heights (h1 front, h2 back; pad included, Q16 결정). */
export function bearingBlockRebar(model: PierModel): BlockRebar[] {
  return model.blocks.map((b) => ({
    no: b.no,
    row: b.row,
    bars: blockBars(b.row === '전열' ? model.h1 * 1000 : model.h2 * 1000),
  }));
}

/** Total bars of one pier: bars per block × blocks, for S1 and S2 separately. */
export function totals(rebar: BlockRebar[]): { S1: number; S2: number } {
  return rebar.reduce(
    (sum, blk) => {
      for (const bar of blk.bars) sum[bar.name] += bar.count;
      return sum;
    },
    { S1: 0, S2: 0 },
  );
}