import path from "node:path";
import { globSync } from "glob";
import MarkdownDocument from "./document.js";

/**
 * Load documents from an Obsidian vault
 * @param vaultPath The path to the vault to load
 * @param ignorePatterns A glob pattern to ignore files for
 * @returns A promise which resolves as an array of laoded Documents
 */
function loadVaultDocuments(
  vault: Vault,
  ignorePatterns: string[] = [],
): MarkdownDocument[] {
  const discoveredMarkdownDocuments = globSync(`${vault.vaultPath}/**/*.md`, {
    ignore: ignorePatterns,
  });

  const markdownDocuments: MarkdownDocument[] = [];

  for (const filePath of discoveredMarkdownDocuments) {
    const file = new MarkdownDocument(filePath, vault);

    if (markdownDocuments.some((check) => check.slug === file.slug)) {
      throw new Error("Duplicate slug: " + file.slug);
    }

    markdownDocuments.push(file);
  }

  return markdownDocuments;
}

/**
 * Build a VaultIndex from a list of loaded Documents
 * @param vaultDocs An array of all the documents to index
 * @returns A VaultIndex, which is an object that maps document slugs to information
 */
function buildVaultIndex(
  vaultDocs: MarkdownDocument[],
): Record<string, MarkdownDocument> {
  const index: Record<string, MarkdownDocument> = {};

  for (const document of vaultDocs) {
    index[document.slug] = document;
  }

  return index;
}

class VaultView {
  /** An array of all discovered Markdown documents */
  documents: MarkdownDocument[] = [];

  /** An array of all generated document slugs */
  slugs: string[] = [];

  /** A map of generated document slugs to their associated document */
  index: Record<string, MarkdownDocument> = {};

  /** The absolute path of this fault on disk */
  readonly vault: Vault;

  /** The number of documents in this vault */
  readonly size: number = 0;

  constructor(documents: MarkdownDocument[], vault: Vault) {
    this.documents = documents;
    this.slugs = documents.map((doc) => doc.slug);
    this.index = buildVaultIndex(documents);
    this.vault = vault;
    this.size = documents.length;
  }

  /**
   * Map over each document in this view, modifying it as needed
   * @param fn A function to map over every document in this view
   * @returns A reference to this view to chain additional calls
   */
  process(fn: (document: MarkdownDocument) => void): VaultView {
    this.documents.forEach(fn);
    return this;
  }

  /**
   * Utility function to chain function calls back to the original vault
   * @returns A reference to the vault that produced this view
   */
  unscope(): Vault {
    return this.vault;
  }
}

interface VaultOptions {
  ignorePatterns?: string[];
}

export default class Vault {
  /** An array of all discovered Markdown documents */
  documents: MarkdownDocument[] = [];

  /** An array of all generated document slugs */
  slugs: string[] = [];

  /** A map of generated document slugs to their associated document */
  index: Record<string, MarkdownDocument> = {};

  /** The absolute path of this fault on disk */
  readonly vaultPath: string;

  /** The number of documents in this vault */
  readonly size: number = 0;

  /** File patterns to ignore when discovering vault files */
  private ignorePatterns: string[] = [];

  constructor(vaultRootPath: string, options?: VaultOptions) {
    this.vaultPath = path.resolve(vaultRootPath);
    this.ignorePatterns = options?.ignorePatterns ?? [];

    const allFiles = loadVaultDocuments(this, this.ignorePatterns);
    const allSlugs = allFiles.map((doc) => doc.slug);

    this.documents = allFiles;
    this.slugs = allSlugs;
    this.size = allFiles.length;
    this.index = buildVaultIndex(allFiles);
  }

  scope(fn: (document: MarkdownDocument) => boolean): VaultView {
    const matchingDocs = this.documents.filter(fn);
    return new VaultView(matchingDocs, this);
  }

  /**
   * Map over each document in this vault, modifying it as needed
   * @param fn A function to map over every document in this vault
   * @returns A reference to this vault to chain additional calls
   */
  process(fn: (document: MarkdownDocument) => void): Vault {
    this.documents.forEach(fn);
    return this;
  }

  write(): Vault {
    this.documents.forEach((doc) => {
      doc.write();
    });

    return this;
  }
}