// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//
// This file has been modified for use by the TinyGo compiler.

;(() => {
  // Map multiple JavaScript environments to a single common API,
  // preferring web standards over Node.js API.
  //
  // Environments considered:
  // - Browsers
  // - Node.js
  // - Electron
  // - Parcel

  if (typeof global !== 'undefined') {
    // global already exists
  } else if (typeof window !== 'undefined') {
    window.global = window
  } else if (typeof self !== 'undefined') {
    self.global = self
  } else {
    throw new Error('cannot export Go (neither global, window nor self is defined)')
  }

  if (!global.require && typeof require !== 'undefined') {
    global.require = require
  }

  if (!global.fs && global.require) {
    global.fs = require('fs')
  }

  const enosys = () => {
    const err = new Error('not implemented')
    err.code = 'ENOSYS'
    return err
  }

  if (!global.fs) {
    let outputBuf = ''
    global.fs = {
      constants: { O_WRONLY: -1, O_RDWR: -1, O_CREAT: -1, O_TRUNC: -1, O_APPEND: -1, O_EXCL: -1 }, // unused
      writeSync(fd, buf) {
        outputBuf += decoder.decode(buf)
        const nl = outputBuf.lastIndexOf('\n')
        if (nl != -1) {
          console.log(outputBuf.substr(0, nl))
          outputBuf = outputBuf.substr(nl + 1)
        }
        return buf.length
      },
      write(fd, buf, offset, length, position, callback) {
        if (offset !== 0 || length !== buf.length || position !== null) {
          callback(enosys())
          return
        }
        const n = this.writeSync(fd, buf)
        callback(null, n)
      },
      chmod(path, mode, callback) {
        callback(enosys())
      },
      chown(path, uid, gid, callback) {
        callback(enosys())
      },
      close(fd, callback) {
        callback(enosys())
      },
      fchmod(fd, mode, callback) {
        callback(enosys())
      },
      fchown(fd, uid, gid, callback) {
        callback(enosys())
      },
      fstat(fd, callback) {
        callback(enosys())
      },
      fsync(fd, callback) {
        callback(null)
      },
      ftruncate(fd, length, callback) {
        callback(enosys())
      },
      lchown(path, uid, gid, callback) {
        callback(enosys())
      },
      link(path, link, callback) {
        callback(enosys())
      },
      lstat(path, callback) {
        callback(enosys())
      },
      mkdir(path, perm, callback) {
        callback(enosys())
      },
      open(path, flags, mode, callback) {
        callback(enosys())
      },
      read(fd, buffer, offset, length, position, callback) {
        callback(enosys())
      },
      readdir(path, callback) {
        callback(enosys())
      },
      readlink(path, callback) {
        callback(enosys())
      },
      rename(from, to, callback) {
        callback(enosys())
      },
      rmdir(path, callback) {
        callback(enosys())
      },
      stat(path, callback) {
        callback(enosys())
      },
      symlink(path, link, callback) {
        callback(enosys())
      },
      truncate(path, length, callback) {
        callback(enosys())
      },
      unlink(path, callback) {
        callback(enosys())
      },
      utimes(path, atime, mtime, callback) {
        callback(enosys())
      }
    }
  }

  if (!global.process) {
    global.process = {
      getuid() {
        return -1
      },
      getgid() {
        return -1
      },
      geteuid() {
        return -1
      },
      getegid() {
        return -1
      },
      getgroups() {
        throw enosys()
      },
      pid: -1,
      ppid: -1,
      umask() {
        throw enosys()
      },
      cwd() {
        throw enosys()
      },
      chdir() {
        throw enosys()
      }
    }
  }

  if (!global.crypto) {
    const nodeCrypto = require('crypto')
    global.crypto = {
      getRandomValues(b) {
        nodeCrypto.randomFillSync(b)
      }
    }
  }

  if (!global.performance) {
    global.performance = {
      now() {
        const [sec, nsec] = process.hrtime()
        return sec * 1000 + nsec / 1000000
      }
    }
  }

  if (!global.TextEncoder) {
    global.TextEncoder = require('util').TextEncoder
  }

  if (!global.TextDecoder) {
    global.TextDecoder = require('util').TextDecoder
  }

  // End of polyfills for common API.

  const encoder = new TextEncoder('utf-8')
  const decoder = new TextDecoder('utf-8')
  var logLine = []

  global.Go = class {
    constructor() {
      this._callbackTimeouts = new Map()
      this._nextCallbackTimeoutID = 1

      const mem = () => {
        // The buffer may change when requesting more memory.
        return new DataView(this._inst.exports.memory.buffer)
      }

      const setInt64 = (addr, v) => {
        mem().setUint32(addr + 0, v, true)
        mem().setUint32(addr + 4, Math.floor(v / 4294967296), true)
      }

      const getInt64 = (addr) => {
        const low = mem().getUint32(addr + 0, true)
        const high = mem().getInt32(addr + 4, true)
        return low + high * 4294967296
      }

      const loadValue = (addr) => {
        const f = mem().getFloat64(addr, true)
        if (f === 0) {
          return undefined
        }
        if (!isNaN(f)) {
          return f
        }

        const id = mem().getUint32(addr, true)
        return this._values[id]
      }

      const storeValue = (addr, v) => {
        const nanHead = 0x7ff80000

        if (typeof v === 'number') {
          if (isNaN(v)) {
            mem().setUint32(addr + 4, nanHead, true)
            mem().setUint32(addr, 0, true)
            return
          }
          if (v === 0) {
            mem().setUint32(addr + 4, nanHead, true)
            mem().setUint32(addr, 1, true)
            return
          }
          mem().setFloat64(addr, v, true)
          return
        }

        switch (v) {
          case undefined:
            mem().setFloat64(addr, 0, true)
            return
          case null:
            mem().setUint32(addr + 4, nanHead, true)
            mem().setUint32(addr, 2, true)
            return
          case true:
            mem().setUint32(addr + 4, nanHead, true)
            mem().setUint32(addr, 3, true)
            return
          case false:
            mem().setUint32(addr + 4, nanHead, true)
            mem().setUint32(addr, 4, true)
            return
        }

        let id = this._ids.get(v)
        if (id === undefined) {
          id = this._idPool.pop()
          if (id === undefined) {
            id = this._values.length
          }
          this._values[id] = v
          this._goRefCounts[id] = 0
          this._ids.set(v, id)
        }
        this._goRefCounts[id]++
        let typeFlag = 1
        switch (typeof v) {
          case 'string':
            typeFlag = 2
            break
          case 'symbol':
            typeFlag = 3
            break
          case 'function':
            typeFlag = 4
            break
        }
        mem().setUint32(addr + 4, nanHead | typeFlag, true)
        mem().setUint32(addr, id, true)
      }

      const loadSlice = (array, len, cap) => {
        return new Uint8Array(this._inst.exports.memory.buffer, array, len)
      }

      const loadSliceOfValues = (array, len, cap) => {
        const a = new Array(len)
        for (let i = 0; i < len; i++) {
          a[i] = loadValue(array + i * 8)
        }
        return a
      }

      const loadString = (ptr, len) => {
        return decoder.decode(new DataView(this._inst.exports.memory.buffer, ptr, len))
      }

      const timeOrigin = Date.now() - performance.now()
      this.importObject = {
        wasi_snapshot_preview1: {
          // https://github.com/WebAssembly/WASI/blob/main/phases/snapshot/docs.md#fd_write
          fd_write: function (fd, iovs_ptr, iovs_len, nwritten_ptr) {
            let nwritten = 0
            if (fd == 1) {
              for (let iovs_i = 0; iovs_i < iovs_len; iovs_i++) {
                let iov_ptr = iovs_ptr + iovs_i * 8 // assuming wasm32
                let ptr = mem().getUint32(iov_ptr + 0, true)
                let len = mem().getUint32(iov_ptr + 4, true)
                nwritten += len
                for (let i = 0; i < len; i++) {
                  let c = mem().getUint8(ptr + i)
                  if (c == 13) {
                    // CR
                    // ignore
                  } else if (c == 10) {
                    // LF
                    // write line
                    let line = decoder.decode(new Uint8Array(logLine))
                    logLine = []
                    console.log(line)
                  } else {
                    logLine.push(c)
                  }
                }
              }
            } else {
              console.error('invalid file descriptor:', fd)
            }
            mem().setUint32(nwritten_ptr, nwritten, true)
            return 0
          },
          fd_close: () => 0, // dummy
          fd_fdstat_get: () => 0, // dummy
          fd_seek: () => 0, // dummy
          proc_exit: (code) => {
            if (global.process) {
              // Node.js
              process.exit(code)
            } else {
              // Can't exit in a browser.
              throw 'trying to exit with code ' + code
            }
          },
          random_get: (bufPtr, bufLen) => {
            crypto.getRandomValues(loadSlice(bufPtr, bufLen))
            return 0
          }
        },
        env: {
          // func ticks() float64
          'runtime.ticks': () => {
            return timeOrigin + performance.now()
          },

          // func sleepTicks(timeout float64)
          'runtime.sleepTicks': (timeout) => {
            // Do not sleep, only reactivate scheduler after the given timeout.
            setTimeout(this._inst.exports.go_scheduler, timeout)
          },

          // func finalizeRef(v ref)
          'syscall/js.finalizeRef': (v_addr) => {
            // Note: TinyGo does not support finalizers so this is only called
            // for one specific case, by js.go:jsString.
            const id = mem().getUint32(v_addr, true)
            this._goRefCounts[id]--
            if (this._goRefCounts[id] === 0) {
              const v = this._values[id]
              this._values[id] = null
              this._ids.delete(v)
              this._idPool.push(id)
            }
          },

          // func stringVal(value string) ref
          'syscall/js.stringVal': (ret_ptr, value_ptr, value_len) => {
            const s = loadString(value_ptr, value_len)
            storeValue(ret_ptr, s)
          },

          // func valueGet(v ref, p string) ref
          'syscall/js.valueGet': (retval, v_addr, p_ptr, p_len) => {
            let prop = loadString(p_ptr, p_len)
            let value = loadValue(v_addr)
            let result = Reflect.get(value, prop)
            storeValue(retval, result)
          },

          // func valueSet(v ref, p string, x ref)
          'syscall/js.valueSet': (v_addr, p_ptr, p_len, x_addr) => {
            const v = loadValue(v_addr)
            const p = loadString(p_ptr, p_len)
            const x = loadValue(x_addr)
            Reflect.set(v, p, x)
          },

          // func valueDelete(v ref, p string)
          'syscall/js.valueDelete': (v_addr, p_ptr, p_len) => {
            const v = loadValue(v_addr)
            const p = loadString(p_ptr, p_len)
            Reflect.deleteProperty(v, p)
          },

          // func valueIndex(v ref, i int) ref
          'syscall/js.valueIndex': (ret_addr, v_addr, i) => {
            storeValue(ret_addr, Reflect.get(loadValue(v_addr), i))
          },

          // valueSetIndex(v ref, i int, x ref)
          'syscall/js.valueSetIndex': (v_addr, i, x_addr) => {
            Reflect.set(loadValue(v_addr), i, loadValue(x_addr))
          },

          // func valueCall(v ref, m string, args []ref) (ref, bool)
          'syscall/js.valueCall': (ret_addr, v_addr, m_ptr, m_len, args_ptr, args_len, args_cap) => {
            const v = loadValue(v_addr)
            const name = loadString(m_ptr, m_len)
            const args = loadSliceOfValues(args_ptr, args_len, args_cap)
            try {
              const m = Reflect.get(v, name)
              storeValue(ret_addr, Reflect.apply(m, v, args))
              mem().setUint8(ret_addr + 8, 1)
            } catch (err) {
              storeValue(ret_addr, err)
              mem().setUint8(ret_addr + 8, 0)
            }
          },

          // func valueInvoke(v ref, args []ref) (ref, bool)
          'syscall/js.valueInvoke': (ret_addr, v_addr, args_ptr, args_len, args_cap) => {
            try {
              const v = loadValue(v_addr)
              const args = loadSliceOfValues(args_ptr, args_len, args_cap)
              storeValue(ret_addr, Reflect.apply(v, undefined, args))
              mem().setUint8(ret_addr + 8, 1)
            } catch (err) {
              storeValue(ret_addr, err)
              mem().setUint8(ret_addr + 8, 0)
            }
          },

          // func valueNew(v ref, args []ref) (ref, bool)
          'syscall/js.valueNew': (ret_addr, v_addr, args_ptr, args_len, args_cap) => {
            const v = loadValue(v_addr)
            const args = loadSliceOfValues(args_ptr, args_len, args_cap)
            try {
              storeValue(ret_addr, Reflect.construct(v, args))
              mem().setUint8(ret_addr + 8, 1)
            } catch (err) {
              storeValue(ret_addr, err)
              mem().setUint8(ret_addr + 8, 0)
            }
          },

          // func valueLength(v ref) int
          'syscall/js.valueLength': (v_addr) => {
            return loadValue(v_addr).length
          },

          // valuePrepareString(v ref) (ref, int)
          'syscall/js.valuePrepareString': (ret_addr, v_addr) => {
            const s = String(loadValue(v_addr))
            const str = encoder.encode(s)
            storeValue(ret_addr, str)
            setInt64(ret_addr + 8, str.length)
          },

          // valueLoadString(v ref, b []byte)
          'syscall/js.valueLoadString': (v_addr, slice_ptr, slice_len, slice_cap) => {
            const str = loadValue(v_addr)
            loadSlice(slice_ptr, slice_len, slice_cap).set(str)
          },

          // func valueInstanceOf(v ref, t ref) bool
          'syscall/js.valueInstanceOf': (v_addr, t_addr) => {
            return loadValue(v_addr) instanceof loadValue(t_addr)
          },

          // func copyBytesToGo(dst []byte, src ref) (int, bool)
          'syscall/js.copyBytesToGo': (ret_addr, dest_addr, dest_len, dest_cap, source_addr) => {
            let num_bytes_copied_addr = ret_addr
            let returned_status_addr = ret_addr + 4 // Address of returned boolean status variable

            const dst = loadSlice(dest_addr, dest_len)
            const src = loadValue(source_addr)
            if (!(src instanceof Uint8Array || src instanceof Uint8ClampedArray)) {
              mem().setUint8(returned_status_addr, 0) // Return "not ok" status
              return
            }
            const toCopy = src.subarray(0, dst.length)
            dst.set(toCopy)
            setInt64(num_bytes_copied_addr, toCopy.length)
            mem().setUint8(returned_status_addr, 1) // Return "ok" status
          },

          // copyBytesToJS(dst ref, src []byte) (int, bool)
          // Originally copied from upstream Go project, then modified:
          //   https://github.com/golang/go/blob/3f995c3f3b43033013013e6c7ccc93a9b1411ca9/misc/wasm/wasm_exec.js#L404-L416
          'syscall/js.copyBytesToJS': (ret_addr, dest_addr, source_addr, source_len, source_cap) => {
            let num_bytes_copied_addr = ret_addr
            let returned_status_addr = ret_addr + 4 // Address of returned boolean status variable

            const dst = loadValue(dest_addr)
            const src = loadSlice(source_addr, source_len)
            if (!(dst instanceof Uint8Array || dst instanceof Uint8ClampedArray)) {
              mem().setUint8(returned_status_addr, 0) // Return "not ok" status
              return
            }
            const toCopy = src.subarray(0, dst.length)
            dst.set(toCopy)
            setInt64(num_bytes_copied_addr, toCopy.length)
            mem().setUint8(returned_status_addr, 1) // Return "ok" status
          }
        }
      }
    }

    async run(instance) {
      this._inst = instance
      this._values = [
        // JS values that Go currently has references to, indexed by reference id
        NaN,
        0,
        null,
        true,
        false,
        global,
        this
      ]
      this._goRefCounts = [] // number of references that Go has to a JS value, indexed by reference id
      this._ids = new Map() // mapping from JS values to reference ids
      this._idPool = [] // unused ids that have been garbage collected
      this.exited = false // whether the Go program has exited

      const mem = new DataView(this._inst.exports.memory.buffer)

      while (true) {
        const callbackPromise = new Promise((resolve) => {
          this._resolveCallbackPromise = () => {
            if (this.exited) {
              throw new Error('bad callback: Go program has already exited')
            }
            setTimeout(resolve, 0) // make sure it is asynchronous
          }
        })
        this._inst.exports._start()
        if (this.exited) {
          break
        }
        await callbackPromise
      }
    }

    _resume() {
      if (this.exited) {
        throw new Error('Go program has already exited')
      }
      this._inst.exports.resume()
      if (this.exited) {
        this._resolveExitPromise()
      }
    }

    _makeFuncWrapper(id) {
      const go = this
      return function () {
        const event = { id: id, this: this, args: arguments }
        go._pendingEvent = event
        go._resume()
        return event.result
      }
    }
  }

  if (
    global.require &&
    global.require.main === module &&
    global.process &&
    global.process.versions &&
    !global.process.versions.electron
  ) {
    if (process.argv.length != 3) {
      console.error('usage: go_js_wasm_exec [wasm binary] [arguments]')
      process.exit(1)
    }

    const go = new Go()
    WebAssembly.instantiate(fs.readFileSync(process.argv[2]), go.importObject)
      .then((result) => {
        return go.run(result.instance)
      })
      .catch((err) => {
        console.error(err)
        process.exit(1)
      })
  }
})()