elysium/apps/api/src/routes/boss.ts

/**
 * @file Boss challenge route handling combat mechanics.
 * @copyright nhcarrigan
 * @license Naomi's Public License
 * @author Naomi Carrigan
 */
/* eslint-disable max-lines-per-function -- Boss handler requires many steps */
/* eslint-disable max-statements -- Boss handler requires many statements */
/* eslint-disable complexity -- Boss handler has inherent complexity */
/* eslint-disable stylistic/max-len -- Long lines in combat logic */
/* eslint-disable max-lines -- Boss route with full combat logic and helpers exceeds line limit */
import { createHmac } from "node:crypto";
import {
  computeSetBonuses,
  getActiveCompanionBonus,
  type BossChallengeResponse,
  type GameState,
} from "@elysium/types";
import { Hono } from "hono";
import { defaultBosses } from "../data/bosses.js";
import { defaultEquipmentSets } from "../data/equipmentSets.js";
import { defaultExplorations } from "../data/explorations.js";
import { prisma } from "../db/client.js";
import { authMiddleware } from "../middleware/auth.js";
import { updateChallengeProgress } from "../services/dailyChallenges.js";
import { logger } from "../services/logger.js";
import type { HonoEnvironment } from "../types/hono.js";

/**
 * Computes the HMAC-SHA256 of data using the given secret.
 * @param data - The data string to sign.
 * @param secret - The HMAC secret key.
 * @returns The hex-encoded HMAC digest.
 */
const computeHmac = (data: string, secret: string): string => {
  return createHmac("sha256", secret).update(data).
    digest("hex");
};

/**
 * Exponential base for the prestige combat multiplier: Math.pow(base, prestigeCount).
 * Replaces the former linear formula (1 + count * 0.1) to enable late-game zone progression.
 * Must be kept in sync with prestigeCombatBase in apps/web/src/engine/tick.ts.
 */
const prestigeCombatBase = 4;

const bossRouter = new Hono<HonoEnvironment>();

bossRouter.use("*", authMiddleware);

const calculatePartyStats = (
  state: GameState,
): { partyDPS: number; partyMaxHp: number } => {
  let globalMultiplier = 1;
  for (const upgrade of state.upgrades) {
    if (upgrade.purchased && upgrade.target === "global") {
      globalMultiplier = globalMultiplier * upgrade.multiplier;
    }
  }

  const prestigeMultiplier = Math.pow(prestigeCombatBase, state.prestige.count);

  // Apply equipped weapon's combat bonus
  // eslint-disable-next-line capitalized-comments -- v8 ignore
  /* v8 ignore next 7 -- @preserve */
  const equipmentCombatMultiplier = state.equipment.
    filter((item) => {
      return item.equipped && item.bonus.combatMultiplier !== undefined;
    }).
    reduce((mult, item) => {
      return mult * (item.bonus.combatMultiplier ?? 1);
    }, 1);

  // eslint-disable-next-line capitalized-comments -- v8 ignore
  /* v8 ignore next 7 -- @preserve */
  const equippedItemIds = state.equipment.
    filter((item) => {
      return item.equipped;
    }).
    map((item) => {
      return item.id;
    });
  const { combatMultiplier: setCombatMultiplier } = computeSetBonuses(
    equippedItemIds,
    defaultEquipmentSets,
  );

  let partyDPS = 0;
  let partyMaxHp = 0;

  for (const adventurer of state.adventurers) {
    if (adventurer.count === 0) {
      continue;
    }

    let adventurerMultiplier = 1;
    for (const upgrade of state.upgrades) {
      if (
        upgrade.purchased
        && upgrade.target === "adventurer"
        && upgrade.adventurerId === adventurer.id
      ) {
        adventurerMultiplier = adventurerMultiplier * upgrade.multiplier;
      }
    }

    const adventurerContribution
      = adventurer.combatPower
        * adventurer.count
        * adventurerMultiplier
        * globalMultiplier
        * prestigeMultiplier;
    partyDPS = partyDPS + adventurerContribution;

    const adventurerHp = adventurer.level * 50 * adventurer.count;
    partyMaxHp = partyMaxHp + adventurerHp;
  }

  // eslint-disable-next-line capitalized-comments -- v8 ignore
  /* v8 ignore next 12 -- @preserve */
  const echoCombatMultiplier = state.transcendence?.echoCombatMultiplier ?? 1;
  const craftedCombatMultiplier
    = state.exploration?.craftedCombatMultiplier ?? 1;

  const companionBonus = getActiveCompanionBonus(
    state.companions?.activeCompanionId ?? null,
    state.companions?.unlockedCompanionIds ?? [],
  );
  const companionCombatMult
    = companionBonus?.type === "bossDamage"
      ? 1 + companionBonus.value
      : 1;

  partyDPS = partyDPS
    * equipmentCombatMultiplier
    * setCombatMultiplier
    * echoCombatMultiplier
    * craftedCombatMultiplier
    * companionCombatMult;

  return { partyDPS, partyMaxHp };
};

bossRouter.post("/challenge", async(context) => {
  try {
    const discordId = context.get("discordId");
    const body = await context.req.json<{ bossId: string }>();

    // eslint-disable-next-line @typescript-eslint/strict-boolean-expressions -- Runtime body validation
    if (!body.bossId) {
      return context.json({ error: "Invalid request body" }, 400);
    }

    const record = await prisma.gameState.findUnique({ where: { discordId } });

    if (!record) {
      return context.json({ error: "No save found" }, 404);
    }

    const rawState: unknown = record.state;
    /* eslint-disable-next-line @typescript-eslint/consistent-type-assertions -- Prisma returns JsonValue; cast to GameState */
    const state = rawState as GameState;
    const boss = state.bosses.find((b) => {
      return b.id === body.bossId;
    });

    if (!boss) {
      return context.json({ error: "Boss not found" }, 404);
    }

    if (boss.status !== "available" && boss.status !== "in_progress") {
      return context.json({ error: "Boss is not currently available" }, 400);
    }

    if (boss.prestigeRequirement > state.prestige.count) {
      return context.json({ error: "Prestige requirement not met" }, 403);
    }

    const { partyDPS, partyMaxHp } = calculatePartyStats(state);

    if (
      partyDPS === 0
      || partyMaxHp === 0
      || !Number.isFinite(partyDPS)
      || !Number.isFinite(partyMaxHp)
    ) {
      return context.json(
        { error: "Your party has no adventurers ready to fight" },
        400,
      );
    }

    const bossHpBefore = boss.currentHp;
    const bossDPS = boss.damagePerSecond;

    const timeToKillBoss = bossHpBefore / partyDPS;
    const timeToKillParty = partyMaxHp / bossDPS;

    const won = timeToKillBoss <= timeToKillParty;

    // eslint-disable-next-line @typescript-eslint/init-declarations -- Conditionally assigned in if/else branches
    let partyHpRemaining: number;
    // eslint-disable-next-line @typescript-eslint/init-declarations -- Conditionally assigned in if/else branches
    let bossHpAtBattleEnd: number;
    // eslint-disable-next-line @typescript-eslint/init-declarations -- Conditionally assigned in if/else branches
    let bossUpdatedHp: number;
    // eslint-disable-next-line @typescript-eslint/init-declarations -- Conditionally assigned based on win/loss
    let rewards: BossChallengeResponse["rewards"];
    // eslint-disable-next-line @typescript-eslint/init-declarations -- Conditionally assigned based on win/loss
    let casualties: BossChallengeResponse["casualties"];

    if (won) {
      bossHpAtBattleEnd = 0;
      bossUpdatedHp = 0;
      const bossDamageDealt = bossDPS * timeToKillBoss;
      partyHpRemaining = Math.max(0, partyMaxHp - bossDamageDealt);

      boss.status = "defeated";
      boss.currentHp = 0;

      const crystalMult = state.prestige.runestonesCrystalMultiplier ?? 1;
      state.resources.gold = state.resources.gold + boss.goldReward;
      state.resources.essence = state.resources.essence + boss.essenceReward;
      const crystalAward = boss.crystalReward * crystalMult;
      state.resources.crystals = state.resources.crystals + crystalAward;
      state.player.totalGoldEarned = state.player.totalGoldEarned + boss.goldReward;

      for (const upgradeId of boss.upgradeRewards) {
        const upgrade = state.upgrades.find((u) => {
          return u.id === upgradeId;
        });
        if (upgrade) {
          upgrade.unlocked = true;
        }
      }

      // Grant equipment rewards — auto-equip if the slot is currently empty
      // eslint-disable-next-line capitalized-comments -- v8 ignore
      /* v8 ignore next 14 -- @preserve */
      for (const equipmentId of boss.equipmentRewards) {
        const equipment = state.equipment.find((item) => {
          return item.id === equipmentId;
        });
        if (equipment) {
          equipment.owned = true;

          const slotAlreadyEquipped = state.equipment.some((item) => {
            return item.type === equipment.type && item.equipped;
          });
          if (!slotAlreadyEquipped) {
            equipment.equipped = true;
          }
        }
      }

      // Unlock next boss in the same zone (zone-based sequential progression)
      const zoneBosses = state.bosses.filter((b) => {
        return b.zoneId === boss.zoneId;
      });
      const zoneIndex = zoneBosses.findIndex((b) => {
        return b.id === body.bossId;
      });
      const [ nextZoneBoss ] = zoneBosses.slice(zoneIndex + 1);
      if (
        nextZoneBoss
        && nextZoneBoss.prestigeRequirement <= state.prestige.count
      ) {
        const nextBossInState = state.bosses.find((b) => {
          return b.id === nextZoneBoss.id;
        });
        if (nextBossInState) {
          nextBossInState.status = "available";
        }
      }

      /*
       * Unlock any zone whose unlock conditions are now both satisfied
       * (final boss defeated AND final quest completed)
       */
      // eslint-disable-next-line capitalized-comments -- v8 ignore
      /* v8 ignore next -- @preserve */
      for (const zone of state.zones) {
        if (zone.status === "unlocked") {
          continue;
        }
        if (zone.unlockBossId !== body.bossId) {
          continue;
        }

        // Boss condition just became satisfied — check the quest condition too
        const questSatisfied
          = zone.unlockQuestId === null
          || state.quests.some((q) => {
            return q.id === zone.unlockQuestId && q.status === "completed";
          });
        if (!questSatisfied) {
          continue;
        }
        zone.status = "unlocked";

        // Unlock exploration areas for the newly unlocked zone
        for (const area of state.exploration?.areas ?? []) {
          const areaDefinition = defaultExplorations.find((explorationArea) => {
            return explorationArea.id === area.id;
          });
          // eslint-disable-next-line capitalized-comments -- v8 ignore
          /* v8 ignore next 3 -- @preserve */
          if (areaDefinition?.zoneId === zone.id && area.status === "locked") {
            area.status = "available";
          }
        }

        const updatedZoneBosses = state.bosses.filter((b) => {
          return b.zoneId === zone.id;
        });
        const [ firstUpdatedBoss ] = updatedZoneBosses;
        if (
          firstUpdatedBoss
          && firstUpdatedBoss.prestigeRequirement <= state.prestige.count
        ) {
          firstUpdatedBoss.status = "available";
        }
      }

      // Update daily boss challenge progress
      if (state.dailyChallenges) {
        const { crystalsAwarded, updatedChallenges } = updateChallengeProgress(
          state.dailyChallenges,
          "bossesDefeated",
          1,
        );
        state.dailyChallenges = updatedChallenges;
        state.resources.crystals = state.resources.crystals + crystalsAwarded;
      }

      // First-kill bounty — only awarded once across all prestiges
      const staticBoss = defaultBosses.find((b) => {
        return b.id === body.bossId;
      });

      // eslint-disable-next-line capitalized-comments -- v8 ignore
      /* v8 ignore next 7 -- @preserve */
      const bountyRunestones
        = boss.bountyRunestonesClaimed === true
          ? 0
          : staticBoss?.bountyRunestones ?? 0;
      if (bountyRunestones > 0) {
        boss.bountyRunestonesClaimed = true;
      }
      state.prestige.runestones = state.prestige.runestones + bountyRunestones;

      rewards = {
        bountyRunestones: bountyRunestones,
        crystals:         crystalAward,
        equipmentIds:     boss.equipmentRewards,
        essence:          boss.essenceReward,
        gold:             boss.goldReward,
        upgradeIds:       boss.upgradeRewards,
      };
    } else {
      const partyDamageDealt = partyDPS * timeToKillParty;
      bossHpAtBattleEnd = Math.max(0, bossHpBefore - partyDamageDealt);
      bossUpdatedHp = boss.maxHp;
      partyHpRemaining = 0;

      boss.status = "available";
      boss.currentHp = boss.maxHp;

      // How close was the party to winning? (0 = hopeless, 1 = nearly won)
      const victoryProgress = Math.min(1, timeToKillParty / timeToKillBoss);
      // Casualty rate scales from ~0% (nearly won) to 60% (completely outmatched)
      const casualtyFraction = (1 - victoryProgress) * 0.6;

      casualties = [];
      for (const adventurer of state.adventurers) {
        if (adventurer.count === 0) {
          continue;
        }
        const killed = Math.floor(adventurer.count * casualtyFraction);
        if (killed > 0) {
          adventurer.count = Math.max(1, adventurer.count - killed);
          casualties.push({ adventurerId: adventurer.id, killed: killed });
        }
      }
    }

    const now = Date.now();
    await prisma.gameState.update({
      /* eslint-disable-next-line @typescript-eslint/consistent-type-assertions -- Prisma requires object */
      data:  { state: state as object, updatedAt: now },
      where: { discordId },
    });

    const secret = process.env.ANTI_CHEAT_SECRET;
    const updatedSignature = secret === undefined
      ? undefined
      : computeHmac(JSON.stringify(state), secret);

    const { bossId } = body;
    void logger.metric("boss_challenge", 1, { bossId, discordId, won });

    const bossMaxHp = boss.maxHp;
    const bossNewHp = bossUpdatedHp;
    const response: BossChallengeResponse = {
      bossDPS,
      bossHpAtBattleEnd,
      bossHpBefore,
      bossMaxHp,
      bossNewHp,
      partyDPS,
      partyHpRemaining,
      partyMaxHp,
      won,
    };
    if (rewards !== undefined) {
      response.rewards = rewards;
    }
    if (casualties !== undefined) {
      response.casualties = casualties;
    }
    if (updatedSignature !== undefined) {
      response.signature = updatedSignature;
    }

    return context.json(response);
  } catch (error) {
    void logger.error(
      "boss_challenge",
      error instanceof Error
        ? error
        : new Error(String(error)),
    );
    return context.json({ error: "Internal server error" }, 500);
  }
});

export { bossRouter };