import fs from "node:fs";
import path from "node:path";
import Database from "better-sqlite3";

import type { Action } from "./contracts/action";
import type { Entity } from "./contracts/entity";
import type { SceneRulebook } from "./contracts/rulebook";
import type { Turn } from "./contracts/turn";
import type { ValidationResult } from "./contracts/validation";
import type { WorldState } from "./contracts/world";

export interface DatabaseConfig {
  dbPath: string;
}

export interface CharacterGardenDatabase {
  sqlite: Database.Database;
  init(): void;
  close(): void;
  upsertEntities(entities: Entity[]): void;
  listEntities(): Entity[];
  insertTurn(turn: Turn): void;
  listTurns(): Turn[];
  insertActions(turnId: string, actions: Action[]): void;
  insertValidationResults(turnId: string, results: ValidationResult[]): void;
  insertWorldState(turnId: string | null, worldState: WorldState): void;
  getLatestWorldState(): WorldState | null;
  upsertRulebook(rulebook: SceneRulebook): void;
  getRulebook(id: string): SceneRulebook | null;
  listRulebooks(): SceneRulebook[];
  deleteRulebook(id: string): void;
  wipe(): void;
}

function ensureParentDirectory(dbPath: string): void {
  fs.mkdirSync(path.dirname(dbPath), { recursive: true });
}

function parseJson<T>(value: string): T {
  return JSON.parse(value) as T;
}

export function createDatabase(config: DatabaseConfig): CharacterGardenDatabase {
  ensureParentDirectory(config.dbPath);
  const sqlite = new Database(config.dbPath);

  const initStatements = [
    `
      CREATE TABLE IF NOT EXISTS turns (
        id TEXT PRIMARY KEY,
        raw_text TEXT NOT NULL,
        created_at INTEGER NOT NULL
      )
    `,
    `
      CREATE TABLE IF NOT EXISTS actions (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        turn_id TEXT NOT NULL,
        action_index INTEGER NOT NULL,
        actor_id TEXT NOT NULL,
        type TEXT NOT NULL,
        target_id TEXT,
        location_id TEXT,
        metadata_json TEXT,
        FOREIGN KEY(turn_id) REFERENCES turns(id)
      )
    `,
    `
      CREATE TABLE IF NOT EXISTS validation_results (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        turn_id TEXT NOT NULL,
        action_index INTEGER NOT NULL,
        success INTEGER NOT NULL,
        reason TEXT,
        message TEXT,
        FOREIGN KEY(turn_id) REFERENCES turns(id)
      )
    `,
    `
      CREATE TABLE IF NOT EXISTS entities (
        id TEXT PRIMARY KEY,
        name TEXT NOT NULL,
        type TEXT NOT NULL,
        attributes_json TEXT NOT NULL
      )
    `,
    `
      CREATE TABLE IF NOT EXISTS world_states (
        id TEXT PRIMARY KEY,
        turn_id TEXT,
        state_json TEXT NOT NULL,
        created_at INTEGER NOT NULL,
        FOREIGN KEY(turn_id) REFERENCES turns(id)
      )
    `,
    `
      CREATE TABLE IF NOT EXISTS rulebooks (
        id TEXT PRIMARY KEY,
        world_id TEXT NOT NULL,
        name TEXT NOT NULL,
        description TEXT,
        rules_json TEXT NOT NULL,
        created_at INTEGER NOT NULL,
        updated_at INTEGER NOT NULL
      )
    `,
  ];

  for (const statement of initStatements) {
    sqlite.exec(statement);
  }

  const clearEntitiesStatement = sqlite.prepare("DELETE FROM entities");
  const upsertEntityStatement = sqlite.prepare(`
    INSERT INTO entities (id, name, type, attributes_json)
    VALUES (@id, @name, @type, @attributes_json)
    ON CONFLICT(id) DO UPDATE SET
      name = excluded.name,
      type = excluded.type,
      attributes_json = excluded.attributes_json
  `);

  const listEntitiesStatement = sqlite.prepare(`
    SELECT id, name, type, attributes_json
    FROM entities
    ORDER BY id ASC
  `);

  const insertTurnStatement = sqlite.prepare(`
    INSERT INTO turns (id, raw_text, created_at)
    VALUES (@id, @raw_text, @created_at)
  `);

  const listTurnsStatement = sqlite.prepare(`
    SELECT id, raw_text, created_at
    FROM turns
    ORDER BY created_at ASC
  `);

  const insertActionStatement = sqlite.prepare(`
    INSERT INTO actions (
      turn_id,
      action_index,
      actor_id,
      type,
      target_id,
      location_id,
      metadata_json
    ) VALUES (
      @turn_id,
      @action_index,
      @actor_id,
      @type,
      @target_id,
      @location_id,
      @metadata_json
    )
  `);

  const insertValidationStatement = sqlite.prepare(`
    INSERT INTO validation_results (
      turn_id,
      action_index,
      success,
      reason,
      message
    ) VALUES (
      @turn_id,
      @action_index,
      @success,
      @reason,
      @message
    )
  `);

  const insertWorldStateStatement = sqlite.prepare(`
    INSERT INTO world_states (id, turn_id, state_json, created_at)
    VALUES (@id, @turn_id, @state_json, @created_at)
  `);

  const latestWorldStateStatement = sqlite.prepare(`
    SELECT state_json
    FROM world_states
    ORDER BY created_at DESC
    LIMIT 1
  `);

  const upsertRulebookStatement = sqlite.prepare(`
    INSERT INTO rulebooks (id, world_id, name, description, rules_json, created_at, updated_at)
    VALUES (@id, @world_id, @name, @description, @rules_json, @created_at, @updated_at)
    ON CONFLICT(id) DO UPDATE SET
      name = excluded.name,
      description = excluded.description,
      rules_json = excluded.rules_json,
      updated_at = excluded.updated_at
  `);

  const getRulebookStatement = sqlite.prepare(`
    SELECT id, world_id, name, description, rules_json, created_at, updated_at
    FROM rulebooks
    WHERE id = @id
  `);

  const listRulebooksStatement = sqlite.prepare(`
    SELECT id, world_id, name, description, rules_json, created_at, updated_at
    FROM rulebooks
    ORDER BY created_at ASC
  `);

  const deleteRulebookStatement = sqlite.prepare(`
    DELETE FROM rulebooks WHERE id = @id
  `);

  return {
    sqlite,

    init() {
      // Tables are initialized on construction.
    },

    close() {
      sqlite.close();
    },

    wipe() {
      sqlite.exec(`
        DELETE FROM validation_results;
        DELETE FROM actions;
        DELETE FROM world_states;
        DELETE FROM turns;
        DELETE FROM entities;
      `);
    },

    upsertEntities(entities) {
      const tx = sqlite.transaction((entityList: Entity[]) => {
        clearEntitiesStatement.run();
        for (const entity of entityList) {
          upsertEntityStatement.run({
            id: entity.id,
            name: entity.name,
            type: entity.type,
            attributes_json: JSON.stringify(entity.attributes),
          });
        }
      });

      tx(entities);
    },

    listEntities() {
      const rows = listEntitiesStatement.all() as Array<{
        id: string;
        name: string;
        type: string;
        attributes_json: string;
      }>;

      return rows.map((row) => ({
        id: row.id,
        name: row.name,
        type: row.type,
        attributes: parseJson<Record<string, unknown>>(row.attributes_json),
      }));
    },

    insertTurn(turn) {
      insertTurnStatement.run({
        id: turn.id,
        raw_text: turn.rawText,
        created_at: turn.createdAt,
      });
    },

    listTurns() {
      const rows = listTurnsStatement.all() as Array<{
        id: string;
        raw_text: string;
        created_at: number;
      }>;

      return rows.map((row) => ({
        id: row.id,
        rawText: row.raw_text,
        actions: [],
        validation: [],
        createdAt: row.created_at,
      }));
    },

    insertActions(turnId, actions) {
      const tx = sqlite.transaction((actionList: Action[]) => {
        actionList.forEach((action, index) => {
          insertActionStatement.run({
            turn_id: turnId,
            action_index: index,
            actor_id: action.actorId,
            type: action.type,
            target_id: action.targetId ?? null,
            location_id: action.locationId ?? null,
            metadata_json: action.metadata ? JSON.stringify(action.metadata) : null,
          });
        });
      });

      tx(actions);
    },

    insertValidationResults(turnId, results) {
      const tx = sqlite.transaction((validationList: ValidationResult[]) => {
        for (const result of validationList) {
          insertValidationStatement.run({
            turn_id: turnId,
            action_index: result.actionIndex,
            success: result.success ? 1 : 0,
            reason: result.reason ?? null,
            message: result.message ?? null,
          });
        }
      });

      tx(results);
    },

    insertWorldState(turnId, worldState) {
      insertWorldStateStatement.run({
        id: worldState.id,
        turn_id: turnId,
        state_json: JSON.stringify(worldState),
        created_at: worldState.createdAt,
      });
    },

    getLatestWorldState() {
      const row = latestWorldStateStatement.get() as { state_json: string } | undefined;
      if (!row) {
        return null;
      }
      return parseJson<WorldState>(row.state_json);
    },

    upsertRulebook(rulebook) {
      upsertRulebookStatement.run({
        id: rulebook.id,
        world_id: rulebook.worldId,
        name: rulebook.name,
        description: rulebook.description ?? null,
        rules_json: JSON.stringify(rulebook.rules),
        created_at: rulebook.createdAt,
        updated_at: rulebook.updatedAt,
      });
    },

    getRulebook(id) {
      const row = getRulebookStatement.get({ id }) as
        | {
            id: string;
            world_id: string;
            name: string;
            description: string | null;
            rules_json: string;
            created_at: number;
            updated_at: number;
          }
        | undefined;
      if (!row) return null;
      return {
        id: row.id,
        worldId: row.world_id,
        name: row.name,
        description: row.description ?? undefined,
        rules: parseJson(row.rules_json),
        createdAt: row.created_at,
        updatedAt: row.updated_at,
      };
    },

    listRulebooks() {
      const rows = listRulebooksStatement.all() as Array<{
        id: string;
        world_id: string;
        name: string;
        description: string | null;
        rules_json: string;
        created_at: number;
        updated_at: number;
      }>;
      return rows.map((row) => ({
        id: row.id,
        worldId: row.world_id,
        name: row.name,
        description: row.description ?? undefined,
        rules: parseJson(row.rules_json),
        createdAt: row.created_at,
        updatedAt: row.updated_at,
      }));
    },

    deleteRulebook(id) {
      deleteRulebookStatement.run({ id });
    },
  };
}