/*
 * v2dom.ts
 * Copyright (C) 2024 veypi <i@veypi.com>
 * 2024-10-23 15:54
 * Distributed under terms of the GPL license.
 */

import proxy from "./proxy"


interface buildOpts<T> {
  id?: string
  typ?: string
  class?: string
  vclass?: [() => string]
  attrs?: attrs
  style?: string
  onclick?: any
  children?: childTyp<T>[] | childTyp<T>
  updator?: (p: HTMLElement) => void
  vbind?: [Object, string]
}

const typs = ['div', 'img', 'span', 'p', 'a', 'input']

type vforChild<T> = { obj: T[], fn: (d: T, idx?: number) => HTMLElement, iterID: string, ifnone: HTMLElement }
type vIfCondition = boolean | number | string | undefined | null | (() => vIfCondition)
type vIfStatment = HTMLElement | (() => HTMLElement)
type vIfChild = { ifID: string, rules: [vIfCondition, vIfStatment][] }
type computedFn = () => number | string | HTMLElement | vforChild<any> | []
type childTyp<T> = HTMLElement | vforChild<T> | string | number | computedFn | vIfChild
type attrs = { [key: string]: string | number | (() => string) }

export const v = <T>(opts: buildOpts<T> | string, children?: childTyp<T> | childTyp<T>[], attrs?: attrs) => {
  if (typeof opts === 'string') {
    if (typs.indexOf(opts) >= 0) {
      opts = { typ: opts }
    } else {
      opts = { class: opts }
    }
  }
  if (children) {
    opts.children = children
  }
  if (attrs) {
    opts.attrs = attrs
  }
  return vbase(opts)
}
export const vspan = (content: string, Class?: string, attrs?: attrs) => {
  return vbase({ typ: 'span', class: Class, children: [content], attrs })
}
export const vbase = <T>(opts: buildOpts<T>) => {
  let dom = document.createElement(opts.typ || 'div')
  if (opts.id) {
    dom.id = opts.id
  }
  if (opts.class) {
    dom.classList.add(...opts.class.split(' '))
  }
  if (opts.vclass) {
    for (let vc of opts.vclass) {
      let oldvc: string[] = []
      proxy.DomListen(dom, () => {
        dom.classList.remove(...oldvc)
        oldvc = vc().split(' ')
        dom.classList.add(...oldvc)
      })
    }
  }
  if (opts.attrs) {
    for (let a in opts.attrs) {
      let attr = opts.attrs[a]
      if (typeof attr === 'function') {
        proxy.DomListen(dom, () => {
          dom.setAttribute(a, attr())
        })
      } else {
        dom.setAttribute(a, String(attr))
      }
    }
  }
  if (opts.onclick) {
    dom.onclick = opts.onclick
  }
  if (opts.children) {
    handleChild(dom, opts.children, true)
  }
  if (opts.style) {
    const regex = /([a-zA-Z-]+)\s*:\s*([^;]+);?/g;
    let match: any
    while ((match = regex.exec(opts.style)) !== null) {
      const key = match[1].trim();
      const value = match[2].trim();
      dom.style.setProperty(key, value)
    }
  }
  dom.setAttribute('voa', '1')
  if (opts.updator) {
    proxy.DomListen(dom, () => {
      opts.updator!(dom)
    })
  }
  if (opts.vbind && opts.typ === 'input') {
    dom.setAttribute('value', Reflect.get(opts.vbind[0], opts.vbind[1]))
    dom.addEventListener('input', (e) => {
      // @ts-ignore
      Reflect.set(opts.vbind[0], opts.vbind[1], e.target.value)
    })
  }
  return dom
}

function handleChild(dom: HTMLElement, c: any, is_only = false, is_listen = false) {
  if (is_only) {
    dom.innerHTML = ''
  }
  if (typeof c === 'function') {
    if (!is_listen) {
      proxy.DomListen(dom, () => {
        handleChild(dom, c(), is_only, true)
      })
    } else {
      handleChild(dom, c(), is_only, true)
    }
  } else if (typeof c === 'string' || typeof c === 'number') {
    dom.innerHTML = String(c)
  } else if (Array.isArray(c)) {
    for (let cc of c) {
      handleChild(dom, cc, is_only && c.length === 1, is_listen)
    }
  } else if (c && c.iterID) {
    handleChildVfor(dom, c as vforChild<any>, is_listen)
  } else if (c && c.ifID) {
    handleChildVif(dom, c as vIfChild, is_listen)
  } else if (c instanceof Element) {
    dom.appendChild(c)
  } else if (typeof c === 'undefined' || c === null) {
  } else {
    console.warn('unknown child type', c)
  }
}

function handleChildVif(dom: HTMLElement, data: vIfChild, is_listen = false) {
  let fn = () => {
    let target = emptyDom()
    for (let r of data.rules) {
      let c = Boolean(r[0])
      if (typeof r[0] === 'function') {
        c = Boolean(r[0]())
      }
      if (c) {
        if (typeof r[1] === 'function') {
          target = r[1]()
        } else {
          target = r[1]
        }
        break
      }
    }
    let before: Element | null = null
    for (let domc of dom.children) {
      if (domc.getAttribute('vbind-if') === data.ifID) {
        before = domc
      }
    }
    target.setAttribute('vbind-if', data.ifID)
    if (before) {
      dom.replaceChild(target, before)
    } else {
      dom.appendChild(target)
    }
  }
  if (is_listen) {
    fn()
  } else {
    proxy.DomListen(dom, fn)
  }
}

export const vif = (...rules: [vIfCondition, vIfStatment][]): vIfChild => {
  let ifID = proxy.GenUniqueID()
  return {
    ifID,
    rules
  }
}

export const vfor = <T>(obj: T[], fn: (d: T, idx?: number) => HTMLElement, ifnone?: () => HTMLElement, iterID?: string): vforChild<T> => {
  if (!iterID) {
    iterID = proxy.GenUniqueID()
  }
  let dom = document.createElement('div') as HTMLElement
  dom.style.display = 'none'
  dom.style.visibility = 'hidden'
  dom.style.height = '0'
  dom.style.width = '0'
  if (ifnone) {
    dom = ifnone()
  }
  dom.setAttribute('vbind-iternone', iterID)
  return {
    obj,
    fn,
    iterID,
    ifnone: dom
  }
}
function handleChildVfor(dom: HTMLElement, data: vforChild<any>, is_listen = false) {
  let fn = () => {
    let itemIDs: string[] = []
    for (let i = 0; i < data.obj.length; i++) {
      let line = data.obj[i]
      let itemID = line[proxy.DataID] || ''
      let nextID = ''
      if (i < data.obj.length - 1) {
        nextID = data.obj[i + 1][proxy.DataID] || ''
      }
      itemIDs.push(itemID)
      let inserted = -1
      let subdom: HTMLElement | null = null
      let beforeChild: HTMLElement | null = null
      let iterFound = false
      for (let childID = 0; childID < dom.children.length; childID++) {
        let child = dom.children[childID]
        // console.log(`${inserted} ${childID} ${itemID} ${nextID}`)
        if (child.getAttribute('vbind-iter') === data.iterID) {
          iterFound = true
          if (child.getAttribute('vbind-iteridx') === itemID) {
            // 找到已存在dom
            inserted = childID
            subdom = child as HTMLElement
          } else if (child.getAttribute('vbind-iteridx') === nextID && nextID != '') {
            // 用于交换位置
            beforeChild = child as HTMLElement
          }
        } else if (child.getAttribute('vbind-iternone') === data.iterID) {
          if (inserted == -1) {
            beforeChild = child as HTMLElement
          }
        } else if (iterFound) {
          if (!beforeChild) {
            beforeChild = child as HTMLElement
          }
          break
        }
      }
      if (inserted == -1) {
        subdom = data.fn(line, i)
        subdom.setAttribute('vbind-iteridx', itemID)
        subdom.setAttribute('vbind-iter', data.iterID)
        if (beforeChild) {
          dom.insertBefore(subdom, beforeChild)
          // console.log(`${iterID} insert new`, subdom)
        } else {
          // console.log(`${iterID} append new`, subdom)
          dom.appendChild(subdom)
        }
      } else if (beforeChild) {
        // console.log(`${iterID} insert old`, subdom)
        dom.insertBefore(subdom!, beforeChild)
      } else {
        // console.log(`${iterID} none`, subdom)
      }
    }
    let noneExist = false
    let removeChilds: Element[] = []
    for (let child of dom.children) {
      if (child.getAttribute('vbind-iter') === data.iterID && itemIDs.indexOf(child.getAttribute('vbind-iteridx') || '') == -1) {
        removeChilds.push(child)
      }
      if (child.getAttribute('vbind-iternone') === data.iterID) {
        noneExist = true
      }
    }
    removeChilds.forEach(e => e.remove())
    if (data.obj.length == 0) {
      if (!noneExist) {
        dom.appendChild(data.ifnone)
      }
    } else {
      if (noneExist) {
        dom.removeChild(data.ifnone)
      }
    }
  }
  if (is_listen) {
    fn()
  } else {
    proxy.DomListen(dom, fn)
  }
}


function emptyDom() {
  let dom = document.createElement('div') as HTMLElement
  dom.style.display = 'none'
  dom.style.visibility = 'hidden'
  dom.style.height = '0'
  dom.style.width = '0'
  return dom
}