import type { Result } from '../../router.ts'
import { METHOD_NAME_ALL } from '../../router.ts'
import type { Pattern } from '../../utils/url.ts'
import { splitPath, splitRoutingPath, getPattern } from '../../utils/url.ts'

type HandlerSet<T> = {
  handler: T
  score: number
  name: string // For debug
}

function findParam<T>(node: Node<T>, name: string): boolean {
  for (let i = 0, len = node.patterns.length; i < len; i++) {
    if (typeof node.patterns[i] === 'object' && node.patterns[i][1] === name) {
      return true
    }
  }
  const nodes = Object.values(node.children)
  for (let i = 0, len = nodes.length; i < len; i++) {
    if (findParam(nodes[i], name)) {
      return true
    }
  }

  return false
}

export class Node<T> {
  methods: Record<string, HandlerSet<T>>[]

  children: Record<string, Node<T>>
  patterns: Pattern[]
  order: number = 0
  name: string
  handlerSetCache: Record<string, HandlerSet<T>[]>

  constructor(method?: string, handler?: T, children?: Record<string, Node<T>>) {
    this.children = children || {}
    this.methods = []
    this.name = ''
    if (method && handler) {
      const m: Record<string, HandlerSet<T>> = {}
      m[method] = { handler: handler, score: 0, name: this.name }
      this.methods = [m]
    }
    this.patterns = []
    this.handlerSetCache = {}
  }

  insert(method: string, path: string, handler: T): Node<T> {
    this.name = `${method} ${path}`
    this.order = ++this.order

    // eslint-disable-next-line @typescript-eslint/no-this-alias
    let curNode: Node<T> = this
    const parts = splitRoutingPath(path)

    const parentPatterns: Pattern[] = []
    const errorMessage = (name: string): string => {
      return `Duplicate param name, use another name instead of '${name}' - ${method} ${path} <--- '${name}'`
    }

    for (let i = 0, len = parts.length; i < len; i++) {
      const p: string = parts[i]

      if (Object.keys(curNode.children).includes(p)) {
        parentPatterns.push(...curNode.patterns)
        curNode = curNode.children[p]
        continue
      }

      curNode.children[p] = new Node()

      const pattern = getPattern(p)
      if (pattern) {
        if (typeof pattern === 'object') {
          for (let j = 0, len = parentPatterns.length; j < len; j++) {
            if (typeof parentPatterns[j] === 'object' && parentPatterns[j][1] === pattern[1]) {
              throw new Error(errorMessage(pattern[1]))
            }
          }
          if (Object.values(curNode.children).some((n) => findParam(n, pattern[1]))) {
            throw new Error(errorMessage(pattern[1]))
          }
        }
        curNode.patterns.push(pattern)
        parentPatterns.push(...curNode.patterns)
      }
      parentPatterns.push(...curNode.patterns)
      curNode = curNode.children[p]
    }

    if (!curNode.methods.length) {
      curNode.methods = []
    }

    const m: Record<string, HandlerSet<T>> = {}

    const handlerSet: HandlerSet<T> = { handler: handler, name: this.name, score: this.order }

    m[method] = handlerSet
    curNode.methods.push(m)

    return curNode
  }

  // getHandlerSets
  private gHSets(node: Node<T>, method: string, wildcard?: boolean): HandlerSet<T>[] {
    return (node.handlerSetCache[`${method}:${wildcard ? '1' : '0'}`] ||= (() => {
      const handlerSets: HandlerSet<T>[] = []
      for (let i = 0, len = node.methods.length; i < len; i++) {
        const m = node.methods[i]
        const handlerSet = m[method] || m[METHOD_NAME_ALL]
        if (handlerSet !== undefined) {
          handlerSets.push(handlerSet)
        }
      }
      return handlerSets
    })())
  }

  search(method: string, path: string): Result<T> | null {
    const handlerSets: HandlerSet<T>[] = []
    const params: Record<string, string> = {}

    // eslint-disable-next-line @typescript-eslint/no-this-alias
    const curNode: Node<T> = this
    let curNodes = [curNode]
    const parts = splitPath(path)

    for (let i = 0, len = parts.length; i < len; i++) {
      const part: string = parts[i]
      const isLast = i === len - 1
      const tempNodes: Node<T>[] = []
      let matched = false

      for (let j = 0, len2 = curNodes.length; j < len2; j++) {
        const node = curNodes[j]
        const nextNode = node.children[part]

        if (nextNode) {
          if (isLast === true) {
            // '/hello/*' => match '/hello'
            if (nextNode.children['*']) {
              handlerSets.push(...this.gHSets(nextNode.children['*'], method, true))
            }
            handlerSets.push(...this.gHSets(nextNode, method))
            matched = true
          } else {
            tempNodes.push(nextNode)
          }
        }

        for (let k = 0, len3 = node.patterns.length; k < len3; k++) {
          const pattern = node.patterns[k]

          // Wildcard
          // '/hello/*/foo' => match /hello/bar/foo
          if (pattern === '*') {
            const astNode = node.children['*']
            if (astNode) {
              handlerSets.push(...this.gHSets(astNode, method))
              tempNodes.push(astNode)
            }
            continue
          }

          if (part === '') continue

          // Named match
          // `/posts/:id` => match /posts/123
          const [key, name, matcher] = pattern

          const child = node.children[key]

          // `/js/:filename{[a-z]+.js}` => match /js/chunk/123.js
          const restPathString = parts.slice(i).join('/')
          if (matcher instanceof RegExp && matcher.test(restPathString)) {
            handlerSets.push(...this.gHSets(child, method))
            params[name] = restPathString
            continue
          }

          if (matcher === true || (matcher instanceof RegExp && matcher.test(part))) {
            if (typeof key === 'string') {
              if (isLast === true) {
                handlerSets.push(...this.gHSets(child, method))
                // `/:id/*` => match `/foo`
                if (child.children['*']) {
                  handlerSets.push(...this.gHSets(child.children['*'], method))
                }
              } else {
                tempNodes.push(child)
              }
            }

            // `/book/a`     => no-slug
            // `/book/:slug` => slug
            // `/book/b`     => no-slug-b
            // GET /book/a   ~> no-slug, param['slug'] => undefined
            // GET /book/foo ~> slug, param['slug'] => foo
            // GET /book/b   ~> no-slug-b, param['slug'] => b
            if (typeof name === 'string' && !matched) {
              params[name] = part
            } else {
              if (node.children[part]) {
                params[name] = part
              }
            }
          }
        }
      }

      curNodes = tempNodes
    }

    const len = handlerSets.length
    if (len === 0) return null
    if (len === 1) return { handlers: [handlerSets[0].handler], params }

    const handlers = handlerSets
      .sort((a, b) => {
        return a.score - b.score
      })
      .map((s) => {
        return s.handler
      })

    return { handlers, params }
  }
}