import { printTree } from "./utils.mjs"

/**
 * Child {
 *   char: 'a',
 *   children: [Child, Child],
 *   path: null / 'full/path',
 *   count: 0
 * }
 */
function Child(char) {
  this.char = char
  this.children = []
  this.path = null
  this.count = 0
}

function buildChild(i, arr) {
  let letter = new Child(arr[0][i])
  let consume = []
  if (arr[0].length === i + 1) {
    letter.path = arr[0]
    letter.count += 1
  } else {
    consume = [arr[0]]
  }

  for (let y = 1; y < arr.length; y++) {
    if (arr[y][i] !== letter.char) break
    consume.push(arr[y])
  }

  letter.count += consume.length
  while (consume.length) {
    letter.children.push(buildChild(i + 1, consume))
    consume.splice(0, letter.children[letter.children.length - 1].count)
  }
  return letter
}

export function buildTree(all) {
  let paths = Array.from(new Set(all)).sort()
  let builder = []
  while (paths.length) {
    builder.push(buildChild(0, paths))
    paths.splice(0, builder[builder.length - 1].count)
  }
  printTree(builder)
  return builder
}

function IfTreeBranch(branches, indent = 0) {
  let output = ''
  let indentation = ''.padStart(indent * 2)

  for (let i = 0; i < branches.length; i++) {
    let branch = branches[i]
    output += `${i > 0 ? 'else ': ''}if (str.charCodeAt(${indent}) === ${branch.char.charCodeAt(0)}) { // ${branch.char}`

    if (branch.path) {
      output += '\n' + indentation + `  if (str.length === ${branch.path.length}) {`
      output += '\n' + indentation + `    return "${branch.path}"`
      output += '\n' + indentation + `  }`
    }
    if (branch.children.length) {
      if (branch.path) {
        output += ' else '
      } else {
        output += '\n' + indentation + '  '
      }
      output += IfTreeBranch(branch.children, indent + 1)
    }
    output += '\n' + indentation + '} '
  }
  return output
}

export function compileTreeIntoIfs(tree) {
  let output = IfTreeBranch(tree)
  output += '\nreturn null'
  return new Function('str', output)
}


function IfTreeBranchBuffer(branches, indent = 0) {
  let output = ''
  let indentation = ''.padStart(indent * 2)

  for (let i = 0; i < branches.length; i++) {
    let branch = branches[i]
    output += `${i > 0 ? 'else ': ''}if (uint[${indent}] === ${branch.char.charCodeAt(0)}) { // ${branch.char}`

    if (branch.path) {
      output += '\n' + indentation + `  if (uint.length === ${branch.path.length}) {`
      output += '\n' + indentation + `    return "${branch.path}"`
      output += '\n' + indentation + `  }`
    }
    if (branch.children.length) {
      if (branch.path) {
        output += ' else '
      } else {
        output += '\n' + indentation + '  '
      }
      output += IfTreeBranchBuffer(branch.children, indent + 1)
    }
    output += '\n' + indentation + '} '
  }
  return output
}

export function compileTreeIntoIfsWithBuffer(tree) {
  let output = `var uint = Buffer.from(str)\n`
  output += IfTreeBranchBuffer(tree)
  output += '\nreturn null'
  return new Function('str', output)
}