const Bucket = require('./bucket');
const { fill, empty, pour } = require('./action');

class Buckets {
  constructor(buckets = []) {
    this.buckets = buckets;
  }

  hasTarget(target) {
    return !!this.buckets.find(bucket => bucket.volume === target)
  }

  performAction(action) {
    if (action.isEmpty()) {
      this.buckets[action.target].empty()
    }
    if (action.isFill()) {
      this.buckets[action.target].fill()
    }
    if (action.isPour()) {
      this.buckets[action.src].pour(this.buckets[action.target])
    }
  }

  possibleActions() {
    const ret = []
    this.buckets.forEach((bucket, index) => {
      if (!bucket.isFull()) {
        ret.push(fill(index));
      }
      if (!bucket.isEmpty()) {
        ret.push(empty(index));
        this.buckets.forEach((dest, j) => {
          if (index === j) {
            return
          }
          if (!dest.isFull()) {
            ret.push(pour(index, j));
          }
        })
      }
    })
    return ret
  }

  string() {
    return this.buckets.map(bucket => bucket.string()).join(', ')
  }

  findTarget(target) {
    const results = {
      mapping: { [this.string()]: [[]] },
      matching: new Set(),
    }
    this._findTarget(target, results, [], 0)

    let best = null

    results.matching.forEach(matchingKey => {
      const result = results.mapping[matchingKey]
      if (best === null) {
        best = result;
        return
      }
      if (best[0].length == result[0].length) {
        best.push(result);
      }
      if (best[0].length > result[0].length) {
        best = result;
      }
    })

    return best || []
  }

  _findTarget(target, state, actions = [], depth = 0) {
    if (this.hasTarget(target)) {
      return
    }
    const possibleActions = this.possibleActions();
    const results = possibleActions.map(action => {
      const copy = fromJSON(this);
      copy.performAction(action);
      return copy;
    });

    const numberOfKeys = Object.keys(state.mapping).length

    results.forEach(((result, i) => {
      const key = result.string();
      const existingActions = state.mapping[key];
      const action = possibleActions[i];

      if (result.hasTarget(target)) {
        state.matching.add(result.string());
      }

      if (!existingActions) {
        state.mapping[key] = [[...actions, action]]
        return
      }

      if (existingActions[0].length == actions.length + 1) {
        state.mapping[key].push([...actions, possibleActions[i]])
        return
      }

      if (existingActions[0].length > actions.length + 1) {
        state.mapping[key] = [[...actions, action]]
      }
    }));

    if (Object.keys(state.mapping).length === numberOfKeys) {
      return
    }

    results.forEach(((result, i) => {
      const action = possibleActions[i];
      result._findTarget(target, state, [...actions, action], depth + 1)
    }))
  }
}

function fromJSON(json) {
  const jsonStr = JSON.stringify(json)
  const newJSON = JSON.parse(jsonStr)
  const buckets = newJSON.buckets.map(val => new Bucket(val));
  return new Buckets(buckets)
}

module.exports = {
  fromJSON,
  Buckets,
}