const ESC = 0x1b
const GS = 0x1d

/**
 * ESC/POS byte builder — pure, so receipt layout is testable without a
 * printer. Spike scope is ASCII text mode; Indic scripts rasterize in
 * bit-image mode later (09-UX §5.3 print policy).
 */
export class EscPos {
  private bytes: number[] = []

  init(): this {
    this.bytes.push(ESC, 0x40)
    return this
  }

  /** Non-ASCII collapses to '?' in text mode — raster path handles scripts. */
  text(s: string): this {
    for (const ch of s) {
      const code = ch.codePointAt(0)!
      this.bytes.push(code >= 0x20 && code <= 0x7e ? code : 0x3f)
    }
    return this
  }

  line(s = ''): this {
    return this.text(s).newline()
  }

  newline(): this {
    this.bytes.push(0x0a)
    return this
  }

  align(where: 'left' | 'center' | 'right'): this {
    this.bytes.push(ESC, 0x61, where === 'left' ? 0 : where === 'center' ? 1 : 2)
    return this
  }

  bold(on: boolean): this {
    this.bytes.push(ESC, 0x45, on ? 1 : 0)
    return this
  }

  /** Character cell multiplier 1–8 each axis (GS !). */
  size(w: number, h: number): this {
    this.bytes.push(GS, 0x21, ((w - 1) << 4) | (h - 1))
    return this
  }

  feed(lines: number): this {
    this.bytes.push(ESC, 0x64, lines)
    return this
  }

  /** Partial cut with pre-feed (GS V 66). */
  cut(): this {
    this.bytes.push(GS, 0x56, 66, 3)
    return this
  }

  /** Cash-drawer kick pulse on pin 2 (ESC p). Fires on payment, not on print. */
  drawerKick(): this {
    this.bytes.push(ESC, 0x70, 0, 25, 250)
    return this
  }

  build(): Uint8Array {
    return Uint8Array.from(this.bytes)
  }
}

/** Left/right column row padded to exactly `width` chars; left side truncates. */
export function twoCol(left: string, right: string, width: number): string {
  const room = width - right.length - 1
  const l = left.length > room ? left.slice(0, Math.max(0, room)) : left
  return l + ' '.repeat(Math.max(1, width - l.length - right.length)) + right
}

export function hr(width: number): string {
  return '-'.repeat(width)
}