import { camelCase, Dict, paramCase } from 'cosmokit'
import { escapeRegExp } from '@koishijs/utils'
import { h } from '@satorijs/core'
import { Command } from './command'
import { Channel, User } from '../database'
import { Next } from '../middleware'
import { Permissions } from '../permission'
import { Disposable } from 'cordis'
import { Session } from '../session'
import { Context } from '../context'

export interface Token {
  rest?: string
  content: string
  quoted: boolean
  terminator: string
  inters: Argv[]
}

export interface Argv<U extends User.Field = never, G extends Channel.Field = never, A extends any[] = any[], O extends {} = {}> {
  args?: A
  options?: O
  error?: string
  source?: string
  initiator?: string
  terminator?: string
  session?: Session<U, G>
  command?: Command<U, G, A, O>
  rest?: string
  pos?: number
  root?: boolean
  tokens?: Token[]
  name?: string
  next?: Next
}

const leftQuotes = `"'“‘`
const rightQuotes = `"'”’`

export namespace Argv {
  export interface Interpolation {
    terminator?: string
    parse?(source: string): Argv
  }

  const bracs: Dict<Interpolation> = {}

  export function interpolate(initiator: string, terminator: string, parse?: (source: string) => Argv) {
    bracs[initiator] = { terminator, parse }
  }

  interpolate('$(', ')')

  export namespace whitespace {
    export const unescape = (source: string) => source
      .replace(/@__KOISHI_SPACE__@/g, ' ')
      .replace(/@__KOISHI_NEWLINE__@/g, '\n')
      .replace(/@__KOISHI_RETURN__@/g, '\r')
      .replace(/@__KOISHI_TAB__@/g, '\t')

    export const escape = (source: string) => source
      .replace(/ /g, '@__KOISHI_SPACE__@')
      .replace(/\n/g, '@__KOISHI_NEWLINE__@')
      .replace(/\r/g, '@__KOISHI_RETURN__@')
      .replace(/\t/g, '@__KOISHI_TAB__@')
  }

  export class Tokenizer {
    private bracs: Dict<Interpolation>

    constructor() {
      this.bracs = Object.create(bracs)
    }

    interpolate(initiator: string, terminator: string, parse?: (source: string) => Argv) {
      this.bracs[initiator] = { terminator, parse }
    }

    parseToken(source: string, stopReg = '$'): Token {
      const parent = { inters: [] } as Token
      const index = leftQuotes.indexOf(source[0])
      const quote = rightQuotes[index]
      let content = ''
      if (quote) {
        source = source.slice(1)
        stopReg = `${quote}(?=${stopReg})|$`
      }
      stopReg += `|${Object.keys({ ...this.bracs, ...bracs }).map(escapeRegExp).join('|')}`
      const regExp = new RegExp(stopReg)
      while (true) {
        const capture = regExp.exec(source)
        content += whitespace.unescape(source.slice(0, capture.index))
        if (capture[0] in this.bracs) {
          source = source.slice(capture.index + capture[0].length).trimStart()
          const { parse, terminator } = this.bracs[capture[0]]
          const argv = parse?.(source) || this.parse(source, terminator)
          source = argv.rest
          parent.inters.push({ ...argv, pos: content.length, initiator: capture[0] })
        } else {
          const quoted = capture[0] === quote
          const rest = source.slice(capture.index + +quoted)
          parent.rest = rest.trimStart()
          parent.quoted = quoted
          parent.terminator = capture[0]
          if (quoted) {
            parent.terminator += rest.slice(0, -parent.rest.length)
          } else if (quote) {
            content = leftQuotes[index] + content
            parent.inters.forEach(inter => inter.pos += 1)
          }
          parent.content = content
          if (quote === "'") Argv.revert(parent)
          return parent
        }
      }
    }

    parse(source: string, terminator = ''): Argv {
      const tokens: Token[] = []
      source = h.parse(source).map((el) => {
        return el.type === 'text' ? el.toString() : whitespace.escape(el.toString())
      }).join('')
      let rest = source, term = ''
      const stopReg = `\\s+|[${escapeRegExp(terminator)}]|$`
      // eslint-disable-next-line no-unmodified-loop-condition
      while (rest && !(terminator && rest.startsWith(terminator))) {
        const token = this.parseToken(rest, stopReg)
        tokens.push(token)
        rest = token.rest
        term = token.terminator
        delete token.rest
      }
      if (rest.startsWith(terminator)) rest = rest.slice(1)
      source = source.slice(0, -(rest + term).length)
      rest = whitespace.unescape(rest)
      source = whitespace.unescape(source)
      return { tokens, rest, source }
    }

    stringify(argv: Argv) {
      const output = argv.tokens.reduce((prev, token) => {
        if (token.quoted) prev += leftQuotes[rightQuotes.indexOf(token.terminator[0])] || ''
        return prev + token.content + token.terminator
      }, '')
      if (argv.rest && !rightQuotes.includes(output[output.length - 1]) || argv.initiator) {
        return output.slice(0, -1)
      }
      return output
    }
  }

  const defaultTokenizer = new Tokenizer()

  export function parse(source: string, terminator = '') {
    return defaultTokenizer.parse(source, terminator)
  }

  export function stringify(argv: Argv) {
    return defaultTokenizer.stringify(argv)
  }

  export function revert(token: Token) {
    while (token.inters.length) {
      const { pos, source, initiator } = token.inters.pop()
      token.content = token.content.slice(0, pos)
        + initiator + source + bracs[initiator].terminator
        + token.content.slice(pos)
    }
  }

  // builtin domains
  export interface Domain {
    el: h[]
    elements: h[]
    string: string
    number: number
    boolean: boolean
    text: string
    rawtext: string
    user: string
    channel: string
    integer: number
    posint: number
    natural: number
    bigint: bigint
    date: Date
    img: JSX.IntrinsicElements['img']
    image: JSX.IntrinsicElements['img']
    audio: JSX.IntrinsicElements['audio']
    video: JSX.IntrinsicElements['video']
    file: JSX.IntrinsicElements['file']
  }

  export type DomainType = keyof Domain

  type ParamType<S extends string, F>
    = S extends `${any}:${infer T}` ? T extends DomainType ? Domain[T] : F : F

  type Replace<S extends string, X extends string, Y extends string>
    = S extends `${infer L}${X}${infer R}` ? `${L}${Y}${Replace<R, X, Y>}` : S

  type ExtractAll<S extends string, F>
    = S extends `${infer L}]${infer R}` ? [ParamType<L, F>, ...ExtractAll<R, F>] : []

  type ExtractFirst<S extends string, F>
    = S extends `${infer L}]${any}` ? ParamType<L, F> : boolean

  type ExtractSpread<S extends string> = S extends `${infer L}...${infer R}`
    ? [...ExtractAll<L, string>, ...ExtractFirst<R, string>[]]
    : [...ExtractAll<S, string>, ...string[]]

  export type ArgumentType<S extends string> = ExtractSpread<Replace<S, '>', ']'>>

  export type OptionType<S extends string> = ExtractFirst<Replace<S, '>', ']'>, any>

  export type Type = DomainType | RegExp | readonly string[] | Transform<any> | DomainConfig<any>

  export interface Declaration {
    name?: string
    type?: Type
    fallback?: any
    variadic?: boolean
    required?: boolean
  }

  export type Transform<T> = (source: string, session: Session) => T

  export interface DomainConfig<T = any> {
    transform?: Transform<T>
    greedy?: boolean
    numeric?: boolean
  }

  export interface OptionConfig<T extends Type = Type> extends Permissions.Config {
    aliases?: string[]
    symbols?: string[]
    value?: any
    fallback?: any
    type?: T
    descPath?: string
  }

  export interface TypedOptionConfig<T extends Type> extends OptionConfig<T> {
    type: T
  }

  export interface OptionVariant extends OptionConfig {
    syntax: string
  }

  export interface OptionDeclaration extends Declaration, OptionVariant {
    values: Dict<any>
    /** @deprecated */
    valuesSyntax: Dict<string>
    variants: Dict<OptionVariant>
  }

  type OptionDeclarationMap = Dict<OptionDeclaration>

  export namespace CommandBase {
    export interface Config {
      strictOptions?: boolean
    }
  }

  // do not use lookbehind assertion for Safari compatibility
  const SYNTAX = /(?:-[\w\x80-\uffff-]*|[^,\s\w\x80-\uffff]+)/.source
  const BRACKET = /((?:\s*\[[^\]]+?\]|\s*<[^>]+?>)*)/.source
  const OPTION_REGEXP = new RegExp(`^(${SYNTAX}(?:,\\s*${SYNTAX})*(?=\\s|$))?${BRACKET}(.*)$`)

  export class CommandBase<T extends CommandBase.Config = CommandBase.Config> {
    public declaration: string

    public _arguments: Declaration[]
    public _options: OptionDeclarationMap = {}
    public _disposables: Disposable[] = []

    private _namedOptions: OptionDeclarationMap = {}
    private _symbolicOptions: OptionDeclarationMap = {}

    constructor(public readonly name: string, declaration: string, public ctx: Context, public config: T) {
      if (!name) throw new Error('expect a command name')
      const declList = this._arguments = ctx.$commander.parseDecl(declaration)
      this.declaration = declList.stripped
      for (const decl of declList) {
        this._disposables.push(this.ctx.i18n.define('', `commands.${this.name}.arguments.${decl.name}`, decl.name))
      }
    }

    _createOption(name: string, def: string, config: OptionConfig) {
      const cap = OPTION_REGEXP.exec(def)
      const param = paramCase(name)
      let syntax = cap[1] || '--' + param
      const bracket = cap[2] || ''
      const desc = cap[3].trim()

      const aliases: string[] = config.aliases ?? []
      const symbols: string[] = config.symbols ?? []
      for (let param of syntax.trim().split(',')) {
        param = param.trimStart()
        const name = param.replace(/^-+/, '')
        if (!name || !param.startsWith('-')) {
          symbols.push(h.escape(param))
        } else {
          aliases.push(name)
        }
      }

      if (!('value' in config) && !aliases.includes(param)) {
        syntax += ', --' + param
      }

      const declList = this.ctx.$commander.parseDecl(bracket.trimStart())
      if (declList.stripped) syntax += ' ' + declList.stripped
      const option = this._options[name] ||= {
        ...declList[0],
        ...config,
        name,
        values: {},
        valuesSyntax: {},
        variants: {},
        syntax,
      }

      let path = `commands.${this.name}.options.${name}`
      const fallbackType = typeof option.fallback
      if ('value' in config) {
        path += '.' + config.value
        option.variants[config.value] = { ...config, syntax }
        option.valuesSyntax[config.value] = syntax
        aliases.forEach(name => option.values[name] = config.value)
      } else if (!bracket.trim()) {
        option.type = 'boolean'
      } else if (!option.type && (fallbackType === 'string' || fallbackType === 'number')) {
        option.type = fallbackType
      }

      this._disposables.push(this.ctx.i18n.define('', path, desc))
      this._assignOption(option, aliases, this._namedOptions)
      this._assignOption(option, symbols, this._symbolicOptions)
      if (!this._namedOptions[param]) {
        this._namedOptions[param] = option
      }
    }

    private _assignOption(option: OptionDeclaration, names: readonly string[], optionMap: OptionDeclarationMap) {
      for (const name of names) {
        if (name in optionMap) {
          throw new Error(`duplicate option name "${name}" for command "${this.name}"`)
        }
        optionMap[name] = option
      }
    }

    removeOption<K extends string>(name: K) {
      if (!this._options[name]) return false
      const option = this._options[name]
      delete this._options[name]
      for (const key in this._namedOptions) {
        if (this._namedOptions[key] === option) {
          delete this._namedOptions[key]
        }
      }
      for (const key in this._symbolicOptions) {
        if (this._symbolicOptions[key] === option) {
          delete this._symbolicOptions[key]
        }
      }
      return true
    }

    parse(argv: string | Argv, terminator?: string): Argv {
      if (typeof argv === 'string') {
        argv = Argv.parse(argv, terminator)
      }
      const args = [...argv.args || []]
      const options = { ...argv.options }

      if (!argv.source && argv.tokens) {
        argv.source = this.name + ' ' + Argv.stringify(argv)
      }

      let lastArgDecl: Declaration

      while (!argv.error && argv.tokens?.length) {
        const token = argv.tokens[0]
        let { content, quoted } = token

        // variadic argument
        const argDecl = this._arguments[args.length] || lastArgDecl || {}
        if (args.length === this._arguments.length - 1 && argDecl.variadic) {
          lastArgDecl = argDecl
        }

        // greedy argument
        if (content[0] !== '-' && this.ctx.$commander.resolveDomain(argDecl.type).greedy) {
          args.push(this.ctx.$commander.parseValue(Argv.stringify(argv), 'argument', argv, argDecl))
          break
        }

        // parse token
        argv.tokens.shift()
        let option: OptionDeclaration
        let names: string | string[]
        let param: string
        // symbolic option
        if (!quoted && (option = this._symbolicOptions[content])) {
          names = [paramCase(option.name)]
        } else {
          // normal argument
          if (content[0] !== '-' || quoted || (+content) * 0 === 0 && this.ctx.$commander.resolveDomain(argDecl.type).numeric) {
            args.push(this.ctx.$commander.parseValue(content, 'argument', argv, argDecl))
            continue
          }

          // find -
          let i = 0
          for (; i < content.length; ++i) {
            if (content.charCodeAt(i) !== 45) break
          }

          // find =
          let j = i + 1
          for (; j < content.length; j++) {
            if (content.charCodeAt(j) === 61) break
          }
          const name = content.slice(i, j)
          if (this.config.strictOptions && !this._namedOptions[name]) {
            if (this.ctx.$commander.resolveDomain(argDecl.type).greedy) {
              argv.tokens.unshift(token)
              args.push(this.ctx.$commander.parseValue(Argv.stringify(argv), 'argument', argv, argDecl))
              break
            }
            args.push(this.ctx.$commander.parseValue(content, 'argument', argv, argDecl))
            continue
          }
          if (i > 1 && name.startsWith('no-') && !this._namedOptions[name]) {
            options[camelCase(name.slice(3))] = false
            continue
          }
          names = i > 1 ? [name] : name
          param = content.slice(++j)
          option = this._namedOptions[names[names.length - 1]]
        }

        // get parameter from next token
        quoted = false
        if (!param) {
          const { type, values } = option || {}
          if (this.ctx.$commander.resolveDomain(type).greedy) {
            param = Argv.stringify(argv)
            quoted = true
            argv.tokens = []
          } else {
            // Option has bounded value or option is boolean.
            const isValued = names[names.length - 1] in (values || {}) || type === 'boolean'
            if (!isValued && argv.tokens.length && (type || argv.tokens[0]?.content !== '-')) {
              const token = argv.tokens.shift()
              param = token.content
              quoted = token.quoted
            }
          }
        }

        // handle each name
        for (let j = 0; j < names.length; j++) {
          const name = names[j]
          const optDecl = this._namedOptions[name]
          const key = optDecl ? optDecl.name : camelCase(name)
          if (optDecl && name in optDecl.values) {
            options[key] = optDecl.values[name]
          } else {
            const source = j + 1 < names.length ? '' : param
            options[key] = this.ctx.$commander.parseValue(source, 'option', argv, optDecl)
          }
          if (argv.error) break
        }
      }

      // assign default values
      for (const { name, fallback } of Object.values(this._options)) {
        if (fallback !== undefined && !(name in options)) {
          options[name] = fallback
        }
      }

      delete argv.tokens
      return { ...argv, options, args, error: argv.error || '', command: this as any }
    }

    private stringifyArg(value: any) {
      value = '' + value
      return value.includes(' ') ? `"${value}"` : value
    }

    stringify(args: readonly string[], options: any) {
      let output = this.name
      for (const key in options) {
        const value = options[key]
        if (value === true) {
          output += ` --${key}`
        } else if (value === false) {
          output += ` --no-${key}`
        } else {
          output += ` --${key} ${this.stringifyArg(value)}`
        }
      }
      for (const arg of args) {
        output += ' ' + this.stringifyArg(arg)
      }
      return output
    }
  }
}