/**
 * 频谱渲染器接口
 * 所有频谱特效均需实现此接口
 */
export interface SpectrumRenderer {
  /**
   * 渲染一帧频谱动画
   * @param ctx Canvas 2D 渲染上下文
   * @param bands 频段幅值数组 (0.0 ~ 1.0)
   * @param energy 总体能量值 (0.0 ~ 1.0)
   * @param width Canvas 宽度
   * @param height Canvas 高度
   * @param brandColor 主题品牌色 (hex string, e.g. '#FF0050')
   */
  render(ctx: CanvasRenderingContext2D, bands: number[], energy: number,
    width: number, height: number, brandColor: string, options?: SpectrumRenderOptions): void

  /**
   * 重置渲染器状态
   */
  reset(): void
}

export interface SpectrumRenderOptions {
  complexityScale: number
}

export interface SpectrumPalette {
  primaryHue: number
  warmHue: number
  coolHue: number
  complementaryHue: number
  accentHue: number
}

/**
 * 规范化 hex 颜色字符串，异常时回退到默认值
 */
export function normalizeHexColor(color: string, fallback: string = '#FF0050'): string {
  if (!color || color.length < 7 || color[0] !== '#') {
    return fallback
  }
  const hexBody: string = color.substring(1, 7)
  const valid: boolean = /^[0-9a-fA-F]{6}$/.test(hexBody)
  return valid ? '#' + hexBody : fallback
}

/**
 * 基于品牌色构建频谱调色板（HSL 色相偏移）
 */
export function buildSpectrumPalette(brandColor: string): SpectrumPalette {
  const baseColor: string = normalizeHexColor(brandColor)
  const baseHue: number = hexToHue(baseColor)
  return {
    primaryHue: baseHue,
    warmHue: (baseHue - 28 + 360) % 360,
    coolHue: (baseHue + 28) % 360,
    complementaryHue: (baseHue + 180) % 360,
    accentHue: (baseHue + 55) % 360
  }
}

/**
 * 生成 rgba 字符串，便于 Canvas 透明度控制
 */
export function rgbaFromHex(hex: string, alpha: number): string {
  const safeHex: string = normalizeHexColor(hex)
  const safeAlpha: number = Math.max(0, Math.min(1, alpha))
  const r: number = parseInt(safeHex.substring(1, 3), 16)
  const g: number = parseInt(safeHex.substring(3, 5), 16)
  const b: number = parseInt(safeHex.substring(5, 7), 16)
  return `rgba(${r}, ${g}, ${b}, ${safeAlpha})`
}

/**
 * HSL 转 RGB hex 字符串
 */
export function hslToHex(h: number, s: number, l: number): string {
  const hNorm: number = ((h % 360) + 360) % 360
  const sNorm: number = Math.max(0, Math.min(1, s))
  const lNorm: number = Math.max(0, Math.min(1, l))
  const c: number = (1 - Math.abs(2 * lNorm - 1)) * sNorm
  const x: number = c * (1 - Math.abs((hNorm / 60) % 2 - 1))
  const m: number = lNorm - c / 2
  let r: number = 0
  let g: number = 0
  let b: number = 0

  if (hNorm < 60) { r = c; g = x; b = 0 }
  else if (hNorm < 120) { r = x; g = c; b = 0 }
  else if (hNorm < 180) { r = 0; g = c; b = x }
  else if (hNorm < 240) { r = 0; g = x; b = c }
  else if (hNorm < 300) { r = x; g = 0; b = c }
  else { r = c; g = 0; b = x }

  const ri: number = Math.round((r + m) * 255)
  const gi: number = Math.round((g + m) * 255)
  const bi: number = Math.round((b + m) * 255)

  const toHex = (v: number): string => {
    const hex: string = v.toString(16)
    return hex.length < 2 ? '0' + hex : hex
  }
  return '#' + toHex(ri) + toHex(gi) + toHex(bi)
}

/**
 * 从 hex 字符串解析 HSL 色相
 */
export function hexToHue(hex: string): number {
  let r: number = 0
  let g: number = 0
  let b: number = 0
  if (hex.length >= 7) {
    r = parseInt(hex.substring(1, 3), 16) / 255
    g = parseInt(hex.substring(3, 5), 16) / 255
    b = parseInt(hex.substring(5, 7), 16) / 255
  }
  const max: number = Math.max(r, g, b)
  const min: number = Math.min(r, g, b)
  const d: number = max - min
  let h: number = 0
  if (d !== 0) {
    if (max === r) h = ((g - b) / d) % 6
    else if (max === g) h = (b - r) / d + 2
    else h = (r - g) / d + 4
    h *= 60
    if (h < 0) h += 360
  }
  return h
}