import { readFileSync } from 'node:fs';
import { readdirSync } from 'node:fs';
import path from 'node:path';

import { PRESET_CHARACTERS } from '../src/data/characterPresets.ts';
import { MONSTER_PRESETS_BY_WORLD } from '../src/data/hostileNpcPresets.ts';
import { buildItemCatalogId } from '../src/data/itemCatalog.ts';
import { getScenePresetsByWorld } from '../src/data/scenePresets.ts';
import { buildStateFunctionDefinitions } from '../src/data/stateFunctions.ts';
import { WorldType } from '../src/types.ts';

function readJsonFile<T>(relativePath: string): T {
  const absolutePath = path.resolve(process.cwd(), relativePath);
  return JSON.parse(readFileSync(absolutePath, 'utf8')) as T;
}

function isPlainObject(value: unknown): value is Record<string, unknown> {
  return typeof value === 'object' && value !== null && !Array.isArray(value);
}

function isKnownGender(value: unknown): value is 'male' | 'female' {
  return value === 'male' || value === 'female';
}

function expectPlainObject(errors: string[], label: string, value: unknown) {
  if (!isPlainObject(value)) {
    errors.push(`[override] ${label} must be an object map`);
    return false;
  }
  return true;
}

function validateCharacterOverrides(errors: string[]) {
  const overrides = readJsonFile<Record<string, unknown>>('src/data/characterOverrides.json');
  if (!expectPlainObject(errors, 'characterOverrides', overrides)) return;

  const characterIds = new Set(PRESET_CHARACTERS.map(character => character.id));
  const sceneIds = new Set(
    [WorldType.WUXIA, WorldType.XIANXIA].flatMap(worldType => getScenePresetsByWorld(worldType).map(scene => scene.id)),
  );

  Object.entries(overrides).forEach(([characterId, override]) => {
    if (!characterIds.has(characterId)) {
      errors.push(`[override] characterOverrides contains unknown character id "${characterId}"`);
      return;
    }

    if (!isPlainObject(override)) {
      errors.push(`[override] characterOverrides["${characterId}"] must be an object`);
      return;
    }

    const gender = override.gender;
    if (gender !== undefined && !isKnownGender(gender)) {
      errors.push(`[override] characterOverrides["${characterId}"].gender must be "male" or "female"`);
    }

    const sceneBindings = override.sceneBindings;
    if (sceneBindings !== undefined) {
      if (!isPlainObject(sceneBindings)) {
        errors.push(`[override] characterOverrides["${characterId}"].sceneBindings must be an object`);
      } else {
        Object.entries(sceneBindings).forEach(([worldKey, binding]) => {
          if (!isPlainObject(binding)) {
            errors.push(`[override] characterOverrides["${characterId}"].sceneBindings["${worldKey}"] must be an object`);
            return;
          }

          const homeSceneId = binding.homeSceneId;
          if (homeSceneId !== undefined && (typeof homeSceneId !== 'string' || !sceneIds.has(homeSceneId))) {
            errors.push(`[override] characterOverrides["${characterId}"] has invalid homeSceneId "${String(homeSceneId)}"`);
          }

          const npcSceneIds = binding.npcSceneIds;
          if (npcSceneIds !== undefined) {
            if (!Array.isArray(npcSceneIds) || npcSceneIds.some(sceneId => typeof sceneId !== 'string' || !sceneIds.has(sceneId))) {
              errors.push(`[override] characterOverrides["${characterId}"] has invalid npcSceneIds`);
            }
          }
        });
      }
    }
  });
}

function validateMonsterOverrides(errors: string[]) {
  const overrides = readJsonFile<Record<string, unknown>>('src/data/monsterOverrides.json');
  if (!expectPlainObject(errors, 'monsterOverrides', overrides)) return;

  const hostilePresetIds = new Set(
    [...MONSTER_PRESETS_BY_WORLD[WorldType.WUXIA], ...MONSTER_PRESETS_BY_WORLD[WorldType.XIANXIA]].map(monster => monster.id),
  );

  Object.entries(overrides).forEach(([monsterId, override]) => {
    if (!hostilePresetIds.has(monsterId)) {
      errors.push(`[override] monsterOverrides contains unknown monster id "${monsterId}"`);
      return;
    }
    if (!isPlainObject(override)) {
      errors.push(`[override] monsterOverrides["${monsterId}"] must be an object`);
    }
  });
}

function validateSceneOverrides(errors: string[]) {
  const overrides = readJsonFile<Record<string, unknown>>('src/data/sceneOverrides.json');
  if (!expectPlainObject(errors, 'sceneOverrides', overrides)) return;

  const sceneIds = new Set(
    [WorldType.WUXIA, WorldType.XIANXIA].flatMap(worldType => getScenePresetsByWorld(worldType).map(scene => scene.id)),
  );
  Object.entries(overrides).forEach(([sceneId, override]) => {
    if (!sceneIds.has(sceneId)) {
      errors.push(`[override] sceneOverrides contains unknown scene id "${sceneId}"`);
      return;
    }
    if (!isPlainObject(override)) {
      errors.push(`[override] sceneOverrides["${sceneId}"] must be an object`);
      return;
    }

    const forwardSceneId = override.forwardSceneId;
    if (forwardSceneId !== undefined && (typeof forwardSceneId !== 'string' || !sceneIds.has(forwardSceneId))) {
      errors.push(`[override] sceneOverrides["${sceneId}"] has invalid forwardSceneId "${String(forwardSceneId)}"`);
    }

    const connectedSceneIds = override.connectedSceneIds;
    if (connectedSceneIds !== undefined) {
      if (!Array.isArray(connectedSceneIds) || connectedSceneIds.some(id => typeof id !== 'string' || !sceneIds.has(id))) {
        errors.push(`[override] sceneOverrides["${sceneId}"] has invalid connectedSceneIds`);
      }
    }
  });
}

function validateSceneNpcOverrides(errors: string[]) {
  const overrides = readJsonFile<Record<string, unknown>>('src/data/sceneNpcOverrides.json');
  if (!expectPlainObject(errors, 'sceneNpcOverrides', overrides)) return;

  const npcIds = new Set(
    [WorldType.WUXIA, WorldType.XIANXIA].flatMap(worldType =>
      getScenePresetsByWorld(worldType).flatMap(scene => scene.npcs.map(npc => npc.id)),
    ),
  );
  const characterIds = new Set(PRESET_CHARACTERS.map(character => character.id));

  Object.entries(overrides).forEach(([npcId, override]) => {
    if (!npcIds.has(npcId)) {
      errors.push(`[override] sceneNpcOverrides contains unknown npc id "${npcId}"`);
      return;
    }
    if (!isPlainObject(override)) {
      errors.push(`[override] sceneNpcOverrides["${npcId}"] must be an object`);
      return;
    }

    const gender = override.gender;
    if (gender !== undefined && !isKnownGender(gender)) {
      errors.push(`[override] sceneNpcOverrides["${npcId}"].gender must be "male" or "female"`);
    }

    const characterId = override.characterId;
    if (characterId !== undefined && (typeof characterId !== 'string' || !characterIds.has(characterId))) {
      errors.push(`[override] sceneNpcOverrides["${npcId}"] has invalid characterId "${String(characterId)}"`);
    }
  });
}

function validateStateFunctionOverrides(errors: string[]) {
  const overrides = readJsonFile<Record<string, unknown>>('src/data/stateFunctionOverrides.json');
  if (!expectPlainObject(errors, 'stateFunctionOverrides', overrides)) return;

  const functionIds = new Set(buildStateFunctionDefinitions().map(definition => definition.id));
  Object.entries(overrides).forEach(([functionId, override]) => {
    if (!functionIds.has(functionId)) {
      errors.push(`[override] stateFunctionOverrides contains unknown function id "${functionId}"`);
      return;
    }
    if (!isPlainObject(override)) {
      errors.push(`[override] stateFunctionOverrides["${functionId}"] must be an object`);
    }
  });
}

function validateNpcVisualOverrides(errors: string[]) {
  const overrides = readJsonFile<Record<string, unknown>>('src/data/npcVisualOverrides.json');
  if (!expectPlainObject(errors, 'npcVisualOverrides', overrides)) return;

  const npcIds = new Set(
    [WorldType.WUXIA, WorldType.XIANXIA].flatMap(worldType =>
      getScenePresetsByWorld(worldType).flatMap(scene => scene.npcs.map(npc => npc.id)),
    ),
  );

  Object.entries(overrides).forEach(([npcId, override]) => {
    if (!npcIds.has(npcId)) {
      errors.push(`[override] npcVisualOverrides contains unknown npc id "${npcId}"`);
      return;
    }
    if (!isPlainObject(override)) {
      errors.push(`[override] npcVisualOverrides["${npcId}"] must be an object`);
    }
  });
}

function collectItemAssetPaths(rootDir: string, relativeDir = 'Icons'): string[] {
  const entries = readdirSync(rootDir, { withFileTypes: true });
  const collected: string[] = [];

  entries.forEach(entry => {
    const absolutePath = path.join(rootDir, entry.name);
    const relativePath = `${relativeDir}/${entry.name}`.replace(/\\/g, '/');

    if (entry.isDirectory()) {
      collected.push(...collectItemAssetPaths(absolutePath, relativePath));
      return;
    }

    if (entry.isFile() && entry.name.toLowerCase().endsWith('.png')) {
      collected.push(relativePath);
    }
  });

  return collected;
}

function validateItemOverrides(errors: string[]) {
  const overrides = readJsonFile<Record<string, unknown>>('src/data/itemOverrides.json');
  if (!expectPlainObject(errors, 'itemOverrides', overrides)) return;

  const validItemIds = new Set(
    collectItemAssetPaths(path.resolve(process.cwd(), 'public/Icons'))
      .map(assetPath => buildItemCatalogId(assetPath)),
  );

  Object.entries(overrides).forEach(([itemId, override]) => {
    if (!validItemIds.has(itemId)) {
      errors.push(`[override] itemOverrides contains unknown item id "${itemId}"`);
      return;
    }

    if (!isPlainObject(override)) {
      errors.push(`[override] itemOverrides["${itemId}"] must be an object`);
      return;
    }

    const tags = override.tags;
    if (tags !== undefined) {
      if (!Array.isArray(tags) || tags.some(tag => typeof tag !== 'string' || !tag.trim())) {
        errors.push(`[override] itemOverrides["${itemId}"] has invalid tags`);
      }
    }
  });
}

function main() {
  const errors: string[] = [];

  validateCharacterOverrides(errors);
  validateMonsterOverrides(errors);
  validateSceneOverrides(errors);
  validateSceneNpcOverrides(errors);
  validateStateFunctionOverrides(errors);
  validateNpcVisualOverrides(errors);
  validateItemOverrides(errors);

  if (errors.length > 0) {
    console.error(`Override validation failed with ${errors.length} issue(s):`);
    errors.forEach(error => console.error(`- ${error}`));
    process.exitCode = 1;
    return;
  }

  console.log('Override validation passed.');
}

main();