'use strict';

const stream = require('stream');
const EventEmitter = require('events').EventEmitter;

const commandHandler = require('./command-handler.js');

// function _waitForStart(mod) {
//   return new Promise((resolve)=>{
//     mod.addOnPostRun(resolve);
//   });
// }

// function u8ToBn(u8) {
//   let str = '';
//   for (let i = 0; i < u8.length; i++) {
//     const val = u8[i];
//     str = val.toString(16) + str;
//     if (val < 16) {
//       str = '0' + str;
//     }
//   }
//   return BigInt('0x' + str);
// }

function h8ToBn(HEAPU8, start, len) {
  if (len === 0) {
    return 0n;
  }
  let str = '';
  const fin = start + len * 8;
  for (let i = start; i < fin; i++) {
    const val = HEAPU8[i];
    str = val.toString(16) + str;
    if (val < 16) {
      str = '0' + str;
    }
  }
  return BigInt('0x' + str);
}

// let startCalled = 0;

const bindCWrap = (c, wasm) => {
  const w = wasm.cwrap;
  c.execute    = w('execute',    'number', ['number', 'number', 'number', 'number', 'number', 'array', 'number']);
  c.init       = w('init',       'number', ['number', 'number', 'number', 'number']);
  c.getTime    = w('getTime',    'number', ['number']);
  c.setTrigger = w('setTrigger', 'number', ['number', 'string']);
};

const getWrapper = wasm => {
  // console.log(wasm);

  const c = {};

  let bindCallback;


  const start = async() => {
    // if( !startCalled ) {
    //   await _waitForStart(wasm);
    //   startCalled++;
    // }
    // console.log('s1');
    bindCWrap(c, wasm);
    // console.log('s2');
    bindCallback();
    // console.log('s3');
  };

  // gets a string from a c heap pointer and length
  const getString = (name, len) => {

    // const view = wasm.HEAPU8.subarray(name, name+len);
    // let string = '';
    // for (let i = 0; i < len; i++) {
    //   string += String.fromCharCode(view[i]);
    // }
    // return string;

    let string = '';
    const end = name + len;
    for (let i = name; i < end; i++) {
      string += String.fromCharCode(wasm.HEAPU8[i]);
    }
    return string;

  };

  let boundInfo;

  let boundSet;
  let boundGet;

  let ee = [];

  let boundEE0;
  let boundEE1;

  let context = -1;


  const onEE1 = (
    /* const char* */   eventName,
    /* const size_t */  eventNameLength, // strlen(name)
    /* const int64_t */ time,
    /* const int */     cmd,
    /* const int */     valueWords,
    /* uint64_t* */     value,
    /* const int */     maskWords,
    /* uint64_t* */     mask
  ) => {
    const name = getString(eventName, eventNameLength);
    // console.log(`event name`);
    // console.log({name, time, command, valueWords});



    // const view0 = wasm.HEAPU8.subarray(value, value+(valueWords*8));
    // const view1 = wasm.HEAPU8.subarray(mask,  mask+(valueWords*8));

    // let bigValue = u8ToBn(view0);
    // let bigMask = u8ToBn(view1);
    // let bigValue = 0n;

    // console.log(bigValue.toString(16));

    if (cmd >= 14 && cmd <= 28) {
      ee[1](name, time, cmd);
    } else {
      const bigValue = h8ToBn(wasm.HEAPU8, value, valueWords);
      const bigMask = h8ToBn(wasm.HEAPU8, mask, maskWords);
      ee[1](name, time, cmd, bigValue, bigMask);
    }
  };

  // wasm.addFunction can't be called until after
  // start finishes
  bindCallback = () => {
    boundSet = wasm.addFunction(function(name, len, type, v0, v1) {

      let prop = getString(name, len);
      let tmp;

      switch(type) {
      // set number
      case 0:
        boundInfo[prop] = v0;
        // console.log(`setting ${prop} to ${boundInfo[prop]}`);
        break;
      // set string
      case 1:
        boundInfo[prop] = getString(v0, v1);
        // console.log(`setting ${prop} to ${boundInfo[prop]}`);
        break;
      // set string to path
      case 2:
        break;
      // path to path (any type)
      case 3:
        break;
      // create empty object at path
      case 4:
        break;
      case 5:
        commandHandler(boundInfo, v0, prop);
        break;
      default: throw new Error();
      }


      // viiiii means returns void, accepts int int int int int
    }, 'viiiii');

    boundGet = wasm.addFunction(function(name, len) {
      let prop = getString(name, len);
      return prop;
    }, 'iii');


    boundEE0 = wasm.addFunction(function(name, len) {
      ee[0](getString(name, len));
    }, 'vii');

    boundEE1 = wasm.addFunction(onEE1, 'viijiiiii');

  };

  return {
    start,
    c,
    init: (cb0, cb1, info) => {
      boundInfo = info;
      ee[0] = cb0;
      ee[1] = cb1;
      context = c.init(boundEE0, boundEE1, boundSet, boundGet);
      return context;
    },
    execute: (ctx, cb0, cb1, info, chunk) => {
      boundInfo = info;
      ee[0] = cb0;
      ee[1] = cb1;
      return c.execute(ctx, boundEE0, boundEE1, boundSet, boundGet, chunk, chunk.length);
    },
    setTrigger: (ctx, triggerString) => {
      return c.setTrigger(ctx, triggerString);
    },
    getTime: (ctx) => {
      return BigInt(c.getTime(ctx));
    }
  };

};

module.exports = async wasm => {
  const lib = getWrapper(wasm);
  // console.log('getWrapper', lib);
  await lib.start();
  // console.log('vcd wasm srarted');
  const wires = {kind: 'scope', type: '.', name: '.', body: []};
  const info = {stack: [wires], wires};

  const s = new stream.Writable();

  // gets called by c with 1 argument, a string
  const lifemit = s.emit.bind(s);

  const triee = new EventEmitter();

  // gets called by c with 5 arguments
  // string        eventName
  // number        state->time
  // int           command
  // int           state->value
  // int           state->mask

  const triemit = triee.emit.bind(triee);
  let triemit2 = triemit;

  const cxt = lib.init(lifemit, triemit, info);

  s._write = function (chunk, encoding, callback) {
    // console.log('chunk:', chunk.length);
    const err = lib.execute(cxt, lifemit, triemit2, info, chunk);
    if (err) {
      console.log(err);
    }
    // console.log(util.inspect(info, {showHidden: true, depth : null, colorize: true}));
    // console.log(info.stack[0].top);
    // console.log(info.stack[1]);
    // console.log(info.stack[0].top == info.stack[1]);
    callback();
  };

  s.change = {
    on: (id, fn) => {
      triemit2 = triemit;
      triee.on(id, fn);
      const triggerString = triee.eventNames().join(' ') + '  ';
      // console.log(id, Buffer.from(triggerString));
      lib.setTrigger(cxt, triggerString);
    },
    any: fn => {
      triemit2 = fn;
      lib.setTrigger(cxt, '\0');
    }
  };

  s.info = info;

  s.getTime = () => lib.getTime(cxt);

  s.start = lib.start;

  return s;
};