/**
 * Coping heights and Level width (mm) that the coping geometry and the coping rebar depend on (1단계, 승인 2026-10-23).
 * Dependency-free so that both the model and the rebar modules can import it.
 */
export interface CopingGeom {
  /** 끝단 높이 h1 (mm). */
  h1: number;
  /** 테이퍼 높이 h2 (mm). */
  h2: number;
  /** Level 폭 W_L (mm). */
  levelWidth: number;
}

/** P1 values: 끝단 높이 1000, 테이퍼 높이 1500, Level 폭 2100. Used when the input does not give them. */
export const P1_COPING_GEOM: CopingGeom = { h1: 1000, h2: 1500, levelWidth: 2100 };

/** Bar centre to the face of the coping, 127 mm (코핑철근.md §6.1, y_e). */
export const SIDE_COVER_M = 0.127;

/**
 * Side-row levels (EL m) of C12 / C13 (코핑철근.md §6.1). z_0 = Level underside + 127 (the lowest bottom bar's Level
 * height, 41.038 on P1), z_k = z_0 + k·250. The split is by height band:
 *   C12 rows lie in the taper band (Level underside … end underside, height h2);
 *   C13 rows lie in the end band (end underside … top, height h1).
 * zBreak = end underside + 127 is where the taper line starts at the end face (P1: 42.538).
 */
export function sideRowLevels(levelBottom: number, endBottom: number, top?: number): { zBottom: number; zBreak: number; zTop?: number } {
  // Top margin (상면 여유) at least 400 mm (코핑철근.md §6.1): the highest side row lies at or below top − 0.4.
  return { zBottom: levelBottom + SIDE_COVER_M + 0.25, zBreak: endBottom + SIDE_COVER_M, zTop: top === undefined ? undefined : top - SIDE_TOP_MARGIN_M };
}

/** Pitch of the side-row grid (m), and the top margin 400 mm (상면 여유). */
export const SIDE_PITCH_M = 0.25;
export const SIDE_TOP_MARGIN_M = 0.4;