import { Actor } from './actor.js';
import { Graph } from './graph.js';
import { Action } from './action.js';
import { CryptoUtil } from './crypto.js';
import params from '../params.js';

class Post extends Actor {
  constructor(forum, authorPublicKey, postContent) {
    const index = forum.posts.countVertices();
    const name = `Post${index + 1}`;
    super(name, forum.scene);
    this.id = postContent.id ?? CryptoUtil.randomUUID();
    this.authorPublicKey = authorPublicKey;
    this.value = 0;
    this.citations = postContent.citations;
    this.title = postContent.title;
    const revaluationTotal = this.citations.reduce((total, { weight }) => total += Math.abs(weight), 0);
    if (revaluationTotal > params.revaluationLimit) {
      throw new Error('Post revaluation total exceeds revaluation limit '
      + `(${revaluationTotal} > ${params.revaluationLimit})`);
    }
    if (this.citations.some(({ weight }) => Math.abs(weight) > 1)) {
      throw new Error('Each citation weight must be in the range [-1, 1]');
    }
  }
}

/**
 * Purpose: Maintain a directed, acyclic, weighted graph of posts referencing other posts
 */
export class Forum extends Actor {
  constructor(name, scene) {
    super(name, scene);
    this.posts = new Graph(scene);
    this.actions = {
      addPost: new Action('add post', scene),
      propagateValue: new Action('propagate value', this.scene),
    };
  }

  async addPost(authorId, postContent) {
    const post = new Post(this, authorId, postContent);
    await this.actions.addPost.log(this, post);
    this.posts.addVertex(post.id, post, post.title);
    if (this.scene.flowchart) {
      this.scene.flowchart.log(`${post.id} -- value --> ${post.id}_value[0]`);
    }
    for (const { postId: citedPostId, weight } of post.citations) {
      this.posts.addEdge('citation', post.id, citedPostId, { weight });
      if (this.scene.flowchart) {
        this.scene.flowchart.log(`${post.id} -- ${weight} --> ${citedPostId}`);
      }
    }
    return post.id;
  }

  getPost(postId) {
    return this.posts.getVertexData(postId);
  }

  getPosts() {
    return this.posts.getVerticesData();
  }

  async setPostValue(post, value) {
    post.value = value;
    await post.setValue('value', value);
    if (this.scene.flowchart) {
      this.scene.flowchart.log(`${post.id}_value[${value}]`);
    }
  }

  getTotalValue() {
    return this.getPosts().reduce((total, { value }) => total += value, 0);
  }

  async onValidate(bench, pool, postId, initialValue) {
    initialValue *= params.initialPostValue();

    if (this.scene.flowchart) {
      this.scene.flowchart.log(`${postId}_initial_value[${initialValue}] -- initial value --> ${postId}`);
    }

    const post = this.getPost(postId);
    post.setStatus('Validated');

    // Compute rewards
    const rewardsAccumulator = new Map();
    await this.propagateValue(rewardsAccumulator, pool, post, initialValue);

    // Apply computed rewards
    for (const [id, value] of rewardsAccumulator) {
      bench.reputations.addTokens(id, value);
    }
  }

  async propagateValue(rewardsAccumulator, fromActor, post, increment, depth = 0) {
    if (params.referenceChainLimit >= 0 && depth > params.referenceChainLimit) {
      return [];
    }

    this.actions.propagateValue.log(fromActor, post, `(${increment})`);

    // Recursively distribute reputation to citations, according to weights
    let totalOutboundAmount = 0;
    let refundFromOutbound = 0;
    for (const { postId: citedPostId, weight } of post.citations) {
      const citedPost = this.getPost(citedPostId);
      const outboundAmount = weight * increment;
      totalOutboundAmount += outboundAmount;
      refundFromOutbound += await this.propagateValue(rewardsAccumulator, post, citedPost, outboundAmount, depth + 1);
    }

    // Apply leaching value
    const incrementAfterLeaching = increment - (totalOutboundAmount - refundFromOutbound) * params.leachingValue;

    // Prevent value from decreasing below zero
    const rawNewValue = post.value + incrementAfterLeaching;
    const newValue = Math.max(0, rawNewValue);
    // We "refund" the amount that could not be applied.
    // Note that this will always be a negative quantity, because this situation only arises when increment is negative.
    const refundToInbound = rawNewValue - newValue;
    const appliedIncrement = newValue - post.value;

    // Award reputation to post author
    rewardsAccumulator.set(post.authorPublicKey, appliedIncrement);

    // Increment the value of the post
    await this.setPostValue(post, newValue);

    return refundToInbound;
  }
}