const BN = require('bn.js')
const {Long} = require('bytebuffer')
const assert = require('assert')

const types = {
  bytes: () => [bytebuf],
  string: () => [string],
  vector: (type, sorted = true) => [vector, {type, sorted}],
  optional: type => [optional, {type}],
  time: () => [time],
  map: (annotation) => [map, {annotation}],
  static_variant: types => [static_variant, {types}],

  fixed_string16: () => [string, {maxLen: 16}],
  fixed_string32: () => [string, {maxLen: 32}],

  fixed_bytes16: () => [bytebuf, {len: 16}],
  fixed_bytes20: () => [bytebuf, {len: 20}],
  fixed_bytes28: () => [bytebuf, {len: 28}],
  fixed_bytes32: () => [bytebuf, {len: 32}],
  fixed_bytes33: () => [bytebuf, {len: 33}],
  fixed_bytes64: () => [bytebuf, {len: 64}],
  fixed_bytes65: () => [bytebuf, {len: 65}],

  uint8: () => [intbuf, {bits: 8}],
  uint16: () => [intbuf, {bits: 16}],
  uint32: () => [intbuf, {bits: 32}],
  uint64: () => [intbuf, {bits: 64}],
  uint128: () => [bnbuf, {bits: 128}],
  uint224: () => [bnbuf, {bits: 224}],
  uint256: () => [bnbuf, {bits: 256}],
  uint512: () => [bnbuf, {bits: 512}],

  varuint32: () => [intbuf, {bits: 32, variable: true}],

  int8: () => [intbuf, {signed: true, bits: 8}],
  int16: () => [intbuf, {signed: true, bits: 16}],
  int32: () => [intbuf, {signed: true, bits: 32}],
  int64: () => [intbuf, {signed: true, bits: 64}],
  int128: () => [bnbuf, {signed: true, bits: 128}],
  int224: () => [bnbuf, {signed: true, bits: 224}],
  int256: () => [bnbuf, {signed: true, bits: 256}],
  int512: () => [bnbuf, {signed: true, bits: 512}],

  varint32: () => [intbuf, {signed: true, bits: 32, variable: true}],

  float32: () => [float, {bits: 32}],
  float64: () => [float, {bits: 64}]
}

/*
  @arg {SerializerConfig} config
  @return {object} {[typeName]: function(args)}
*/
module.exports = config => {
  config = Object.assign({defaults: false, debug: false, customTypes: {}}, config)

  const allTypes = Object.assign({}, types, config.customTypes)

  const createTypeReducer = baseTypes => (customTypes, name) => {
    customTypes[name] = (...args) => {
      const type = createType(name, config, args, baseTypes, allTypes, customTypes)
      return type
    }
    return customTypes
  }

  const baseTypes = Object.keys(types)
    .reduce(createTypeReducer(), {})

  const customTypes = Object.keys(config.customTypes || {})
    .reduce(createTypeReducer(baseTypes), {})

  return Object.assign({}, baseTypes, customTypes, {config})
}


/**
    @args {string} typeName - matches types[]
    @args {string} config - Additional arguments for types
*/
function createType (typeName, config, args, baseTypes, allTypes, customTypes) {
  const Type = baseTypes ? allTypes[typeName] : types[typeName]
  const [fn, v = {}] = Type(...args)
  const validation = Object.assign(v, config)
  validation.typeName = typeName
  const type = fn(validation, baseTypes, customTypes)
  type.typeName = typeName
  return type
}

const map = validation => {
  const {annotation: [type1, type2]} = validation
  if (!isSerializer(type1)) { throw new TypeError(`map<type1, > unknown`) }
  if (!isSerializer(type2)) { throw new TypeError(`map<, type2> unknown`) }

  return {
    fromByteBuffer (b) {
      const size = b.readVarint32()
      const result = {}
      for (let i = 0; i < size; i++) {
        result[type1.fromByteBuffer(b)] = type2.fromByteBuffer(b)
      }
      if (validation.debug) {
        console.log('0x' + size.toString(16), '(map.fromByteBuffer length)', result)
      }
      return result
    },
    appendByteBuffer (b, value) {
      validate(value, validation)
      const keys = Object.keys(value)
      b.writeVarint32(keys.length)
      if (validation.debug) {
        console.log('0x' + keys.length.toString(16), '(map.appendByteBuffer length)', keys)
      }
      // if(sorted === true) {
      //   value = sortKeys(type1, Object.assign({}, value))
      // }
      for (const o of keys) {
        const value2 = value[o]
        type1.appendByteBuffer(b, o)
        type2.appendByteBuffer(b, value2)
      }
    },
    fromObject (value) {
      validate(value, validation)
      const result = {}
      // if(sorted === true) {
      //   value = sortKeys(type1, Object.assign({}, value))
      // }
      for (const o in value) {
        result[type1.fromObject(o)] = type2.fromObject(value[o])
      }
      return result
    },
    toObject (value) {
      if (validation.defaults && value == null) {
        return {[type1.toObject(null)]: type2.toObject(null)}
      }
      validate(value, validation)
      const result = {}
      // if(sorted === true) {
      //   value = sortKey(type1, Object.assign({}, value))
      // }
      for (const o in value) {
        result[type1.toObject(o)] = type2.toObject(value[o])
      }
      return result
    }
  }
}

const static_variant = validation => {
  const {types} = validation
  return {
    fromByteBuffer (b) {
      const typePosition = b.readVarint32()
      const type = types[typePosition]
      if (validation.debug) {
        console.error(`static_variant id ${typePosition} (0x${typePosition.toString(16)})`)
      }
      assert(type, `static_variant invalid type position ${typePosition}`)
      return [typePosition, type.fromByteBuffer(b)]
    },
    appendByteBuffer(b, object) {
      assert(Array.isArray(object) && object.length === 2, 'Required tuple')
      const typePosition = object[0]
      const type = types[typePosition]
      assert(type, `type ${typePosition}`)
      b.writeVarint32(typePosition)
      type.appendByteBuffer(b, object[1])
    },
    fromObject(object) {
      assert(Array.isArray(object) && object.length === 2, 'Required tuple')
      const typePosition = object[0]
      const type = types[typePosition]
      assert(type, `type ${typePosition}`)
      return [
        typePosition,
        type.fromObject(object[1])
      ]
    },
    toObject(object) {
      if (validation.defaults && object == null) {
        return [0, types[0].toObject(null, debug)]
      }
      assert(Array.isArray(object) && object.length === 2, 'Required tuple')
      const typePosition = object[0]
      const type = types[typePosition]
      assert(type, `type ${typePosition}`)
      return [
        typePosition,
        type.toObject(object[1])
      ]
    }
  }
}

const vector = validation => {
  const {type, sorted} = validation
  if (!isSerializer(type)) {
    throw new TypeError('vector type should be a serializer')
  }

  return {
    fromByteBuffer (b) {
      const size = b.readVarint32()
      if (validation.debug) {
        console.log('fromByteBuffer vector length', size, '(0x' + size.toString(16) + ')')
      }
      const result = []
      for (let i = 0; i < size; i++) {
        result.push(type.fromByteBuffer(b))
      }
      return result
    },
    appendByteBuffer (b, value) {
      if(value == null) {
        value = []
      }
      validate(value, validation)
      b.writeVarint32(value.length)
      if(sorted === true) {
        value = sort(type, Object.assign([], value))
      }
      if (validation.debug) {
        console.log('0x' + value.length.toString(16), '(vector.appendByteBuffer length)', value)
      }
      for (const o of value) {
        type.appendByteBuffer(b, o)
      }
    },
    fromObject (value) {
      if(value == null) {
        value = []
      }
      validate(value, validation)
      let result = []
      for (const o of value) {
        result.push(type.fromObject(o))
      }
      if(sorted === true) {
        result = sort(type, Object.assign([], result))
      }
      return result
    },
    toObject (value) {
      if (validation.defaults && value == null) {
        return [type.toObject(value)]
      }
      if(value == null) {
        value = []
      }
      validate(value, validation)
      if(sorted === true) {
        value = sort(type, Object.assign([], value))
      }
      const result = []
      for (const o of value) {
        result.push(type.toObject(o))
      }
      return result
    }
  }
}

const optional = validation => {
  const {type} = validation
  if (!isSerializer(type)) { throw new TypeError('optional parameter should be a serializer') }

  return {
    fromByteBuffer (b) {
      if (!(b.readUint8() === 1)) {
        return null
      }
      return type.fromByteBuffer(b)
    },
    appendByteBuffer (b, value) {
      if (value != null) {
        b.writeUint8(1)
        type.appendByteBuffer(b, value)
      } else {
        b.writeUint8(0)
      }
    },
    fromObject (value) {
      if (value == null) {
        return null
      }
      return type.fromObject(value)
    },
    toObject (value) {
            // toObject is only null save if defaults is true
      let resultValue
      if (value == null && !validation.defaults) {
        resultValue = null
      } else {
        resultValue = type.toObject(value)
      }
      return resultValue
    }
  }
}

const intbufType = ({signed = false, bits, variable}) =>
    variable ? `Varint${bits}${signed ? 'ZigZag' : ''}` :
    `${signed ? 'Int' : 'Uint'}${bits}`

const intbuf = (validation) => ({
  fromByteBuffer (b) {
    const value = b[`read${intbufType(validation)}`]()
    return Long.isLong(value) ? value.toString() : value
  },
  appendByteBuffer (b, value) {
    // validateInt(value, validation)
    // value = typeof value === 'string' ? Long.fromString(value) : value
    b[`write${intbufType(validation)}`](value)
  },
  fromObject (value) {
    validateInt(value, validation)
    // if(validation.bits > 53 && typeof value === 'number')
    //     value = String(value)

    return value
  },
  toObject (value) {
    if (validation.defaults && value == null) {
      return validation.bits > 53 ? '0' : 0
    }

    validateInt(value, validation)
    // if(validation.bits > 53 && typeof value === 'number')
    //     value = String(value)

    return Long.isLong(value) ? value.toString() : value
  }
})

/** Big Numbers (> 64 bits) */
const bnbuf = (validation) => {
  const {signed = false, bits} = validation
  const size = bits / 8
  return {
    fromByteBuffer (b) {
      const bcopy = b.copy(b.offset, b.offset + size)
      b.skip(size)

      let bn = new BN(bcopy.toHex(), 'hex')
      let buf = bn.toArrayLike(Buffer, 'le', size) // convert to little endian
      bn = new BN(buf.toString('hex'), 'hex')
      if(signed) {
        bn = bn.fromTwos(bits)
      }
      const value = bn.toString()
      validateInt(value, validation)
      return bits > 53 ? value : bn.toNumber()
    },
    appendByteBuffer (b, value) {
      validateInt(value, validation)
      let bn = new BN(value)
      if(signed) {
        bn = bn.toTwos(bits)
      }
      const buf = bn.toArrayLike(Buffer, 'le', size)
      b.append(buf.toString('binary'), 'binary')
    },
    fromObject (value) {
      validateInt(value, validation)
      return value
    },
    toObject (value) {
      if (validation.defaults && value == null) {
        return validation.bits > 53 ? '0' : 0
      }
      validateInt(value, validation)
      return value
    }
  }
}

const floatPoint = require('ieee-float')

const float = (validation) => {
  const {bits} = validation

  // assert(bits === 32 || bits === 64, 'unsupported float bit size: ' + bits)
  const sizeName = bits === 32 ? 'Float' : bits === 64 ? 'Double' : null
  assert(sizeName, 'unsupported float bit size: ' + bits)
  const size = bits / 8

  return {
    fromByteBuffer (b) {
      const bcopy = b.copy(b.offset, b.offset + size)
      b.skip(size)
      const fb = Buffer.from(bcopy.toBinary(), 'binary')
      return floatPoint[`read${sizeName}LE`](fb)
    },
    appendByteBuffer (b, value) {
      const output = []
      floatPoint[`write${sizeName}LE`](output, value)
      b.append(output)
    },
    fromObject (value) {
      return value
    },
    toObject (value) {
      if (validation.defaults && value == null) {
        return 0.0
      }
      return value
    }
  }
}

const bytebuf = (validation) => {
  const _bytebuf = {
    fromByteBuffer (b) {
      const {len} = validation
      let bCopy
      if (len == null) {
        const lenPrefix = b.readVarint32()
        bCopy = b.copy(b.offset, b.offset + lenPrefix)
        b.skip(lenPrefix)
      } else {
        bCopy = b.copy(b.offset, b.offset + len)
        b.skip(len)
      }
      return Buffer.from(bCopy.toBinary(), 'binary')
    },
    appendByteBuffer (b, value) {
      // value = _bytebuf.fromObject(value)

      const {len} = validation
      if (len == null) {
        b.writeVarint32(value.length)
      }
      b.append(value.toString('binary'), 'binary')
    },
    fromObject (value) {
      if (typeof value === 'string') {
        value = Buffer.from(value, 'hex')
      } else if (value instanceof Array) {
        value = Buffer.from(value)
      } else if (value instanceof Uint8Array) {
        value = Buffer.from(value)
      }

      validate(value, validation)
      return value
    },
    toObject (value) {
      const {defaults, len} = validation
      if (defaults && value == null) {
        return Array(len ? len + 1 : 1).join('00')
      }
      validate(value, validation)
      return value.toString('hex')
    },
    compare (a, b) {
      return Buffer.compare(a, b)
    }
  }
  return _bytebuf
}

const string = (validation) => ({
  fromByteBuffer (b) {
    return b.readVString()
  },
  appendByteBuffer (b, value) {
    validate(value, validation)
    b.writeVString(value.toString())
  },
  fromObject (value) {
    validate(value, validation)
    return value
  },
  toObject (value) {
    if (validation.defaults && value == null) {
      return ''
    }
    validate(value, validation)
    return value
  }
})

const time = (validation) => {
  const _time = {
    fromByteBuffer (b) {
      return b.readUint32()
    },
    appendByteBuffer (b, value) {
      // if(typeof value !== "number")
      //     value = _time.fromObject(value)

      validate(value, validation)
      b.writeUint32(value)
    },
    fromObject (value) {
      validate(value, validation)

      if (typeof value === 'number') { return value }

      if (value.getTime) { return Math.floor(value.getTime() / 1000) }

      if (typeof value !== 'string') { throw new Error('Unknown date type: ' + value) }

      // Chrome assumes Zulu when missing, Firefox does not
      if (typeof value === 'string' && !/Z$/.test(value)) { value += 'Z' }

      return Math.floor(new Date(value).getTime() / 1000)
    },
    toObject (value) {
      if (validation.defaults && value == null) { return (new Date(0)).toISOString().split('.')[0] }

      validate(value, validation)

      // if(typeof value === "string") {
      //     if(!/Z$/.test(value))
      //         value += "Z"
      //
      //     return value
      // }

      // if(value.getTime)
      //     return value.toISOString().split('.')[0] + 'Z'

      validateInt(value, spread(validation, {bits: 32}))
      const int = parseInt(value)
      return (new Date(int * 1000)).toISOString().split('.')[0]
    }
  }
  return _time
}

const validate = (value, validation) => {
  if (isEmpty(value)) {
    throw new Error(`Required ${validation.typeName}`)
  }

  if (validation.len != null) {
    if (value.length == null) { throw new Error(`len validation requries a "length" property`) }

    const {len} = validation
    if (value.length !== len) { throw new Error(`${validation.typeName} length ${value.length} does not equal ${len}`) }
  }

  if (validation.maxLen != null) {
    const {maxLen} = validation
    if (value.length == null) { throw new Error(`maxLen validation requries a "length" property`) }

    if (value.length > maxLen) { throw new Error(`${validation.typeName} length ${value.length} exceeds maxLen ${maxLen}`) }
  }
}

const ZERO = new BN()
const ONE = new BN('1')

function validateInt (value, validation) {
  if (isEmpty(value)) {
    throw new Error(`Required ${validation.typeName}`)
  }
  const {signed = false, bits = 54} = validation

  value = String(value).trim()
  if(
    (signed && !/^-?[0-9]+$/.test(value)) ||
    (!signed && !/^[0-9]+$/.test(value))
  ) {
    throw new Error(`Number format ${validation.typeName} ${value}`)
  }

  const max = signed ? maxSigned(bits) : maxUnsigned(bits)
  const min = signed ? minSigned(bits) : ZERO
  const i = new BN(value)

  // console.log('i.toString(), min.toString()', i.toString(), min.toString())
  if (i.cmp(min) < 0 || i.cmp(max) > 0) {
    throw new Error(`Overflow ${validation.typeName} ${value}, ` +
            `max ${max.toString()}, min ${min.toString()}, signed ${signed}, bits ${bits}`)
  }
}

const isSerializer = type =>
  typeof type === 'object' &&
  typeof type.fromByteBuffer === 'function' &&
  typeof type.appendByteBuffer === 'function' &&
  typeof type.fromObject === 'function' &&
  typeof type.toObject === 'function'

const toString = (value, encoding) =>
  value == null ? value :
  value.toString ? value.toString(encoding) :
  value

const sort = (type, values) =>
  type.compare ? values.sort(type.compare) : // custom compare
  values.sort()

const spread = (...args) => Object.assign(...args)
const isEmpty = value => value == null

// 1 << N === Math.pow(2, N)
const maxUnsigned = bits => new BN(1).ishln(bits).isub(ONE)
const maxSigned = bits => new BN(1).ishln(bits - 1).isub(ONE)
const minSigned = bits => new BN(1).ishln(bits - 1).ineg()