import { randomUUID } from 'node:crypto';
import path from 'node:path';
import type { ProjectType } from '../../shared/project-config';
import type { CodingProjectSummary } from '../../shared/coding-project-contracts';
import {
  createCodingProjectMetadata,
  type CodingProjectConfigV2,
} from './project-config';

export interface CodingProject extends CodingProjectSummary {
  path: string;
}

export interface CodingProjectStoreData {
  projects: Record<string, CodingProject>;
  activeProjectId: string | null;
}

export type CodingProjectStoreChange =
  | { type: 'upsert'; project: CodingProject }
  | { type: 'remove'; projectId: string };

export type CodingProjectStoreListener = (change: CodingProjectStoreChange) => void;

export interface CodingProjectStorage {
  read(): Promise<CodingProjectStoreData | undefined>;
  write(data: CodingProjectStoreData): Promise<void>;
}

export interface CodingProjectKeyValueStore {
  get(key: string): unknown;
  set(key: string, value: CodingProjectStoreData): unknown;
}

export type CodingProjectStore = ReturnType<typeof createCodingProjectStore>;

const DEFAULT_PROJECT_STORE_KEY = 'coding-projects-v2';

export function normalizeCodingProjectPath(input: string): string {
  const normalized = path.normalize(path.resolve(input.trim()));
  return process.platform === 'win32' ? normalized.toLowerCase() : normalized;
}

export function createMemoryCodingProjectStorage(
  initial?: CodingProjectStoreData,
): CodingProjectStorage {
  let stored = initial ? structuredClone(initial) : undefined;
  return {
    async read() {
      return stored ? structuredClone(stored) : undefined;
    },
    async write(data) {
      stored = structuredClone(data);
    },
  };
}

export function createCodingProjectStorageFromStore(
  store: CodingProjectKeyValueStore,
  key = DEFAULT_PROJECT_STORE_KEY,
): CodingProjectStorage {
  return {
    async read() {
      const data = store.get(key);
      return data ? structuredClone(data) as CodingProjectStoreData : undefined;
    },
    async write(data) {
      store.set(key, structuredClone(data));
    },
  };
}

export async function createElectronCodingProjectStorage(): Promise<CodingProjectStorage> {
  const Store = (await import('electron-store')).default;
  const store = new Store<{ projects?: CodingProjectStoreData }>({
    // Legacy installed-user storage identity. Renaming it would orphan projects.
    name: 'opencode-projects',
  });
  return createCodingProjectStorageFromStore(store, 'projects');
}

function emptyStoreData(): CodingProjectStoreData {
  return { projects: {}, activeProjectId: null };
}

export function createCodingProjectStore(
  storage: CodingProjectStorage,
  options: {
    createId?: () => string;
    now?: () => string;
  } = {},
) {
  const createId = options.createId ?? randomUUID;
  const now = options.now ?? (() => new Date().toISOString());
  let mutationTail = Promise.resolve();
  const listeners = new Set<CodingProjectStoreListener>();

  function emit(change: CodingProjectStoreChange): void {
    for (const listener of listeners) {
      try {
        listener(change);
      } catch {
        // Persistence must not fail because an observer failed.
      }
    }
  }

  async function readData(): Promise<CodingProjectStoreData> {
    return (await storage.read()) ?? emptyStoreData();
  }

  function mutate<T>(operation: () => Promise<T>): Promise<T> {
    const result = mutationTail.then(operation, operation);
    mutationTail = result.then(() => undefined, () => undefined);
    return result;
  }

  async function upsertProject(input: string, activate: boolean): Promise<CodingProject> {
    return await mutate(async () => {
      const data = await readData();
      const normalizedPath = normalizeCodingProjectPath(input);
      const existing = Object.values(data.projects)
        .find((project) => project.path === normalizedPath);
      const timestamp = now();
      const project: CodingProject = existing
        ? {
            ...existing,
            name: path.basename(normalizedPath),
            updatedAt: timestamp,
            lastOpenedAt: timestamp,
          }
        : {
            id: createId(),
            path: normalizedPath,
            name: path.basename(normalizedPath),
            createdAt: timestamp,
            updatedAt: timestamp,
            lastOpenedAt: timestamp,
          };
      data.projects[project.id] = project;
      if (activate) data.activeProjectId = project.id;
      await storage.write(data);
      emit({ type: 'upsert', project });
      return project;
    });
  }

  return {
    async openFolder(input: string): Promise<CodingProject> {
      return await upsertProject(input, true);
    },

    async rememberProject(input: string): Promise<CodingProject> {
      return await upsertProject(input, false);
    },

    async listProjects(): Promise<CodingProject[]> {
      await mutationTail;
      return Object.values((await readData()).projects)
        .sort((left, right) => right.lastOpenedAt.localeCompare(left.lastOpenedAt));
    },

    async getActiveProject(): Promise<CodingProject | null> {
      await mutationTail;
      const data = await readData();
      return data.activeProjectId ? data.projects[data.activeProjectId] ?? null : null;
    },

    async setActiveProject(projectId: string | null): Promise<CodingProject | null> {
      return await mutate(async () => {
        const data = await readData();
        data.activeProjectId = projectId && data.projects[projectId] ? projectId : null;
        await storage.write(data);
        return data.activeProjectId ? data.projects[data.activeProjectId] : null;
      });
    },

    async removeProject(projectId: string): Promise<void> {
      await mutate(async () => {
        const data = await readData();
        delete data.projects[projectId];
        if (data.activeProjectId === projectId) data.activeProjectId = null;
        await storage.write(data);
        emit({ type: 'remove', projectId });
      });
    },

    subscribe(listener: CodingProjectStoreListener): () => void {
      listeners.add(listener);
      return () => listeners.delete(listener);
    },
  };
}

export async function createLocalCodingProject(
  input: {
    projectPath: string;
    projectType?: ProjectType;
    projectId?: string;
    now?: string;
  },
  store: CodingProjectStore,
): Promise<{ project: CodingProject; config: CodingProjectConfigV2 }> {
  const config = await createCodingProjectMetadata(input.projectPath, {
    projectType: input.projectType,
    projectId: input.projectId,
    now: input.now,
  });
  const project = await store.openFolder(input.projectPath);
  return { project, config };
}