interface Template {
  pattern: string
  weight: number
}

const SHIFT_LOW = [4, 5, 6, 7]
const SHIFT_MID = [8, 9, 10, 11, 12]
const SHIFT_HIGH = [13, 14, 15, 16]
const SHIFTS = [...SHIFT_LOW, ...SHIFT_MID, ...SHIFT_HIGH]

const MASKS = [1, 2, 3, 4, 5, 7, 8, 11, 13, 15, 16, 31, 32, 42, 63, 64, 127, 128, 255]
const MULTIPLIERS = [2, 3, 5, 7, 11, 13]
const MELODIC_MODS = [3, 5, 7, 9, 12, 16, 24, 32, 48, 64, 96, 128, 192, 255]
const DIV_FACTORS = [2, 3, 4, 5, 6, 8, 10, 12, 16, 24, 32]
const SMALL_NUMS = [1, 2, 3, 4, 5, 6, 7, 8]

const TEMPLATES: Template[] = [
  { pattern: "t*(N&t>>S)", weight: 8 },
  { pattern: "t*((t>>S)&N)", weight: 8 },
  { pattern: "t*(N|(t>>S))", weight: 5 },
  { pattern: "(t*X&t>>S1)|(t*X2&t>>S2)", weight: 10 },
  { pattern: "t*(t>>S1|t>>S2)", weight: 10 },
  { pattern: "t*(t>>S1&t>>S2)", weight: 8 },
  { pattern: "(t>>S1)|(t>>S2)", weight: 7 },
  { pattern: "(t>>S1)&(t>>S2)", weight: 7 },
  { pattern: "t&t>>S", weight: 6 },
  { pattern: "(t&t>>S1)*(t>>S2|t>>S3)", weight: 8 },
  { pattern: "(t>>S)&N", weight: 5 },
  { pattern: "t*(t>>S)", weight: 4 },
  { pattern: "(t*X)&(t>>S)", weight: 6 },
  { pattern: "t^(t>>S)", weight: 5 },
  { pattern: "(t>>S1)^(t>>S2)", weight: 6 },
  { pattern: "t*(N&(t>>S1|t>>S2))", weight: 7 },
  { pattern: "((t>>S1)&N)*(t>>S2)", weight: 6 },
  { pattern: "t*((t>>S1)|(t>>S2))&N", weight: 7 },
  { pattern: "(t&(t>>S1))^(t>>S2)", weight: 5 },
  { pattern: "t/(t%(t>>S|t>>S2))", weight: 3 },
  { pattern: "t<<((t>>S1|t>>S2)^(t>>S3))", weight: 4 },
  { pattern: "(t>>S)%(N)", weight: 3 },
  { pattern: "t%(N)+(t>>S)", weight: 4 },
  { pattern: "(t*X&t>>S1)^(t>>S2)", weight: 5 },
  { pattern: "((t>>S1)|(t>>S2))&((t>>S3)|(t>>S4))", weight: 6 },

  { pattern: "t&t>>S", weight: 7 },
  { pattern: "(t>>S1&t>>S2)*t>>S3", weight: 6 },
  { pattern: "(t&(t>>S1))&(t>>S2)", weight: 6 },
  { pattern: "((t>>S1)&t)*(t>>S2&t)", weight: 7 },
  { pattern: "t&(t>>S1)&(t>>S2)", weight: 6 },

  { pattern: "t%(M1)+(t>>S1)%(M2)", weight: 7 },
  { pattern: "(t%M)*(t>>S)", weight: 6 },
  { pattern: "t*((t>>S1)%(M))", weight: 6 },
  { pattern: "(t*(t>>S))%M", weight: 5 },
  { pattern: "(t%M1)^(t>>S)%(M2)", weight: 5 },
  { pattern: "((t>>S)%M1)*(t%M2)", weight: 6 },

  { pattern: "t/(t%(t>>S))", weight: 4 },
  { pattern: "t/(D+(t>>S))", weight: 5 },
  { pattern: "t/(D+(t>>S1|t>>S2))", weight: 5 },
  { pattern: "(t>>S)/(D+(t&N))", weight: 4 },
  { pattern: "t/(D*(t>>S))", weight: 4 },

  { pattern: "t^(t>>S1)^(t>>S2)", weight: 6 },
  { pattern: "((t>>S1)^(t>>S2))*(t>>S3)", weight: 7 },
  { pattern: "(t^t>>S1)&(t^t>>S2)", weight: 6 },
  { pattern: "t^(t>>S1)^(t>>S2)^(t>>S3)", weight: 5 },
  { pattern: "(t^(t>>S1))*(t^(t>>S2))", weight: 6 },

  { pattern: "((t*t)/(t^t>>S))&N", weight: 5 },
  { pattern: "(t*(t>>S1))^(t*(t>>S2))", weight: 6 },
  { pattern: "((t>>S1)*(t>>S2))&((t>>S3)|(t>>S4))", weight: 6 },
  { pattern: "(t&(t>>S1))^((t>>S2)&(t>>S3))", weight: 5 }
]

function randomElement<T>(arr: T[]): T {
  return arr[Math.floor(Math.random() * arr.length)]
}

function fillTemplate(pattern: string): string {
  let formula = pattern

  const sMatches = formula.match(/S\d*/g) || []
  const uniqueShifts = [...new Set(sMatches)]
  uniqueShifts.forEach(placeholder => {
    const shift = randomElement(SHIFTS)
    formula = formula.replace(new RegExp(placeholder, 'g'), shift.toString())
  })

  const nMatches = formula.match(/N\d*/g) || []
  const uniqueMasks = [...new Set(nMatches)]
  uniqueMasks.forEach(placeholder => {
    const mask = randomElement(MASKS)
    formula = formula.replace(new RegExp(placeholder, 'g'), mask.toString())
  })

  const mMatches = formula.match(/M\d*/g) || []
  const uniqueMods = [...new Set(mMatches)]
  uniqueMods.forEach(placeholder => {
    const mod = randomElement(MELODIC_MODS)
    formula = formula.replace(new RegExp(placeholder, 'g'), mod.toString())
  })

  const dMatches = formula.match(/D\d*/g) || []
  const uniqueDivs = [...new Set(dMatches)]
  uniqueDivs.forEach(placeholder => {
    const div = randomElement(DIV_FACTORS)
    formula = formula.replace(new RegExp(placeholder, 'g'), div.toString())
  })

  const xMatches = formula.match(/X\d*/g) || []
  const uniqueMults = [...new Set(xMatches)]
  uniqueMults.forEach(placeholder => {
    const mult = randomElement(MULTIPLIERS)
    formula = formula.replace(new RegExp(placeholder, 'g'), mult.toString())
  })

  return formula
}

function applyParenthesizationRandomization(formula: string): string {
  if (Math.random() < 0.2) {
    const operators = formula.match(/[\+\-\*\/\&\|\^]/g)
    if (operators && operators.length > 0) {
      const parts = formula.split(/([+\-*\/&|^])/)
      if (parts.length >= 3) {
        const idx = Math.floor(Math.random() * (parts.length - 2) / 2) * 2
        parts[idx] = `(${parts[idx]})`
      }
      return parts.join('')
    }
  }
  return formula
}

function applyNegationRandomization(formula: string): string {
  const tMatches = [...formula.matchAll(/\bt\b/g)]
  if (tMatches.length === 0) return formula

  if (Math.random() < 0.1) {
    const idx = Math.floor(Math.random() * tMatches.length)
    const match = tMatches[idx]
    const before = formula.slice(0, match.index!)
    const after = formula.slice(match.index! + 1)
    return before + '(-t)' + after
  }

  if (Math.random() < 0.15) {
    const idx = Math.floor(Math.random() * tMatches.length)
    const match = tMatches[idx]
    const before = formula.slice(0, match.index!)
    const after = formula.slice(match.index! + 1)
    return before + '(~t)' + after
  }

  return formula
}

export function generateRandomFormula(complexity: number = 1): string {
  const complexityWeights = [
    { simple: 0.6, medium: 0.3, complex: 0.1 },
    { simple: 0.3, medium: 0.5, complex: 0.2 },
    { simple: 0.1, medium: 0.3, complex: 0.6 }
  ]

  const weights = complexityWeights[complexity] || complexityWeights[1]

  const filteredTemplates = TEMPLATES.map(t => {
    const patternComplexity = (t.pattern.match(/[SNMDX]\d*/g) || []).length
    let weight = t.weight

    if (patternComplexity <= 2) {
      weight *= weights.simple
    } else if (patternComplexity <= 4) {
      weight *= weights.medium
    } else {
      weight *= weights.complex
    }

    return { ...t, weight }
  })

  const totalWeight = filteredTemplates.reduce((sum, t) => sum + t.weight, 0)
  let random = Math.random() * totalWeight

  let selectedTemplate = filteredTemplates[0]
  for (const template of filteredTemplates) {
    random -= template.weight
    if (random <= 0) {
      selectedTemplate = template
      break
    }
  }

  let formula = fillTemplate(selectedTemplate.pattern)

  formula = applyParenthesizationRandomization(formula)
  formula = applyNegationRandomization(formula)

  const extraLayerChance = complexity === 0 ? 0.10 : complexity === 1 ? 0.20 : 0.35
  if (Math.random() < extraLayerChance) {
    const op = randomElement(['&', '|', '^', '+', '-', '*'])
    const num = randomElement(SMALL_NUMS)
    formula = `(${formula})${op}${num}`
  }

  return formula
}

export function generateFormulaGrid(rows: number, cols: number, complexity: number = 1): string[][] {
  const grid: string[][] = []
  for (let i = 0; i < rows; i++) {
    const row: string[] = []
    for (let j = 0; j < cols; j++) {
      row.push(generateRandomFormula(complexity))
    }
    grid.push(row)
  }
  return grid
}