/**
 * Galaxy Strike Online - Research System
 * Manages the research tree and player tech progress
 */
const RESEARCH_TREE = {
  // ── Weapons ─────────────────────────────────────────────────────────────
  basic_lasers:      { id:'basic_lasers',     name:'Basic Lasers',       branch:'weapons',    tier:1, cost:{credits:500,  gems:0}, time:60,   effects:{weaponDamage:10}, requires:[] },
  pulse_lasers:      { id:'pulse_lasers',     name:'Pulse Lasers',       branch:'weapons',    tier:2, cost:{credits:1200, gems:0}, time:180,  effects:{weaponDamage:25}, requires:['basic_lasers'] },
  advanced_lasers:   { id:'advanced_lasers',  name:'Advanced Lasers',    branch:'weapons',    tier:3, cost:{credits:3000, gems:5}, time:600,  effects:{weaponDamage:50}, requires:['pulse_lasers'] },
  railgun_tech:      { id:'railgun_tech',     name:'Railgun Tech',       branch:'weapons',    tier:2, cost:{credits:2000, gems:0}, time:240,  effects:{armorPierce:20},  requires:['basic_lasers'] },
  smart_warheads:    { id:'smart_warheads',   name:'Smart Warheads',     branch:'weapons',    tier:4, cost:{credits:9000, gems:10},time:1200, effects:{missileBonus:30}, requires:['railgun_tech'] },
  emp_technology:    { id:'emp_technology',   name:'EMP Technology',     branch:'weapons',    tier:3, cost:{credits:4000, gems:5}, time:720,  effects:{empChance:15},    requires:['pulse_lasers'] },
  // ── Engineering ─────────────────────────────────────────────────────────
  structural_analysis:{ id:'structural_analysis', name:'Structural Analysis', branch:'engineering', tier:1, cost:{credits:400,  gems:0}, time:60,   effects:{hullBonus:10},    requires:[] },
  nano_composites:   { id:'nano_composites',  name:'Nano-Composites',    branch:'engineering',tier:2, cost:{credits:1000, gems:0}, time:180,  effects:{hullBonus:25},    requires:['structural_analysis'] },
  reactive_armor:    { id:'reactive_armor',   name:'Reactive Armor',     branch:'engineering',tier:3, cost:{credits:3500, gems:5}, time:600,  effects:{armorBonus:40},   requires:['nano_composites'] },
  improved_engines:  { id:'improved_engines', name:'Improved Engines',   branch:'engineering',tier:1, cost:{credits:300,  gems:0}, time:60,   effects:{speedBonus:10},   requires:[] },
  warp_drive:        { id:'warp_drive',       name:'Warp Drive',         branch:'engineering',tier:5, cost:{credits:20000,gems:20},time:3600, effects:{travelSpeed:60},  requires:['improved_engines'] },
  shield_matrix:     { id:'shield_matrix',    name:'Shield Matrix',      branch:'engineering',tier:2, cost:{credits:1200, gems:0}, time:180,  effects:{shieldRegen:50},  requires:[] },
  // ── Economy ─────────────────────────────────────────────────────────────
  enhanced_mining:   { id:'enhanced_mining',  name:'Enhanced Mining',    branch:'economy',    tier:1, cost:{credits:200,  gems:0}, time:60,   effects:{miningBonus:15},  requires:[] },
  deep_core_drills:  { id:'deep_core_drills', name:'Deep-Core Drills',   branch:'economy',    tier:3, cost:{credits:2500, gems:5}, time:600,  effects:{miningBonus:35},  requires:['enhanced_mining'] },
  trade_protocols:   { id:'trade_protocols',  name:'Trade Protocols',    branch:'economy',    tier:2, cost:{credits:600,  gems:0}, time:120,  effects:{tradeFeeReduction:10}, requires:[] },
  construction_eff:  { id:'construction_eff', name:'Construction Efficiency', branch:'economy', tier:1, cost:{credits:350, gems:0}, time:60,  effects:{buildTimeReduction:10}, requires:[] },
  mass_production:   { id:'mass_production',  name:'Mass Production',    branch:'economy',    tier:4, cost:{credits:10000,gems:10},time:1800, effects:{buildTimeReduction:35}, requires:['construction_eff'] },
  // ── Exploration ─────────────────────────────────────────────────────────
  long_range_sensors:{ id:'long_range_sensors',name:'Long Range Sensors',branch:'exploration',tier:1, cost:{credits:300,  gems:0}, time:60,   effects:{sensorRange:2},   requires:[] },
  stealth_systems:   { id:'stealth_systems',  name:'Stealth Systems',    branch:'exploration',tier:3, cost:{credits:5000, gems:10},time:900,  effects:{stealthRating:30}, requires:['long_range_sensors'] },
  wormhole_nav:      { id:'wormhole_nav',     name:'Wormhole Navigation',branch:'exploration',tier:4, cost:{credits:8000, gems:15},time:1200, effects:{warpCooldown:50}, requires:['long_range_sensors'] },
  // ── Defense ─────────────────────────────────────────────────────────────
  point_defense:     { id:'point_defense',    name:'Point Defense',      branch:'defense',    tier:1, cost:{credits:400,  gems:0}, time:60,   effects:{missileDefense:20}, requires:[] },
  heavy_armor_plating:{ id:'heavy_armor_plating', name:'Heavy Armor Plating', branch:'defense', tier:4, cost:{credits:12000,gems:15},time:1800, effects:{armorBonus:80}, requires:['reactive_armor'] },
  auto_repair:       { id:'auto_repair',      name:'Auto-Repair Drones', branch:'defense',    tier:3, cost:{credits:4000, gems:5}, time:720,  effects:{hullRegen:2},     requires:['shield_matrix'] },
};

class ResearchSystem {
  constructor() {
    this.tree = RESEARCH_TREE;
  }

  getTree() { return Object.values(this.tree); }

  /** Return what a player can currently research */
  getAvailableResearch(playerData) {
    const completed = new Set(playerData.research?.completed || []);
    const inProgress = playerData.research?.inProgress || null;
    return Object.values(this.tree).map(tech => ({
      ...tech,
      status: completed.has(tech.id) ? 'completed'
            : inProgress?.techId === tech.id ? 'in_progress'
            : tech.requires.every(r => completed.has(r)) ? 'available'
            : 'locked',
      progressPercent: inProgress?.techId === tech.id
        ? Math.floor(((Date.now() - inProgress.startedAt) / (tech.time * 1000)) * 100)
        : 0,
    }));
  }

  /** Start researching a technology */
  startResearch(playerData, techId) {
    const tech = this.tree[techId];
    if (!tech) throw new Error('Unknown technology');

    const completed = new Set(playerData.research?.completed || []);
    if (completed.has(techId)) throw new Error('Already researched');
    if (playerData.research?.inProgress) throw new Error('Research already in progress');
    if (!tech.requires.every(r => completed.has(r))) throw new Error('Prerequisites not met');

    const stats = playerData.stats || {};
    if ((stats.credits || 0) < tech.cost.credits) throw new Error(`Need ${tech.cost.credits} credits`);
    if ((stats.gems || 0) < tech.cost.gems) throw new Error(`Need ${tech.cost.gems} gems`);

    stats.credits = (stats.credits || 0) - tech.cost.credits;
    stats.gems    = (stats.gems    || 0) - tech.cost.gems;
    playerData.stats = stats;
    playerData.research = playerData.research || { completed: [], inProgress: null, effects: {} };
    playerData.research.inProgress = { techId, startedAt: Date.now(), completesAt: Date.now() + tech.time * 1000 };
    return { tech, completesAt: playerData.research.inProgress.completesAt };
  }

  /** Check and resolve completed research — call on tick or on request */
  checkCompletion(playerData) {
    const ip = playerData.research?.inProgress;
    if (!ip || Date.now() < ip.completesAt) return null;

    const tech = this.tree[ip.techId];
    playerData.research.completed = playerData.research.completed || [];
    playerData.research.completed.push(ip.techId);
    playerData.research.inProgress = null;
    // Apply effects
    playerData.research.effects = playerData.research.effects || {};
    for (const [k, v] of Object.entries(tech.effects || {})) {
      playerData.research.effects[k] = (playerData.research.effects[k] || 0) + v;
    }
    return tech;
  }

  /** Cancel in-progress research — refund 75% */
  cancelResearch(playerData) {
    const ip = playerData.research?.inProgress;
    if (!ip) throw new Error('No research in progress');
    const tech = this.tree[ip.techId];
    playerData.stats.credits += Math.floor(tech.cost.credits * 0.75);
    playerData.stats.gems    += Math.floor(tech.cost.gems * 0.75);
    playerData.research.inProgress = null;
    return tech;
  }
}

module.exports = { ResearchSystem, RESEARCH_TREE };