import * as async from "async";
import debug from "debug";
import * as N3 from "n3";
import { NamedNode, Parser, Quad, Writer } from "n3";
import * as Immutable from "immutable";
export interface QuadPattern {
  subject: N3.Quad_Subject | null;
  predicate: N3.Quad_Predicate | null;
  object: N3.Quad_Object | null; // literals allowed? needs review. probably 'yes'.
  graph: N3.Quad_Graph | null;
}

const log = debug("patch");

export class Patch {
  // immutable
  private dels: Immutable.Set<Quad>;
  private adds: Immutable.Set<Quad>;
  private _allPredsCache?: Immutable.Set<string>;
  private _allSubjsCache?: Immutable.Set<string>;
  constructor(dels: Iterable<Quad>, adds: Iterable<Quad>) {
    this.dels = Immutable.Set(dels);
    this.adds = Immutable.Set(adds);
    this.validate();
  }

  private validate() {
    // todo: finish porting this from coffeescript
    this.adds.union(this.dels).forEach((q: Quad) => {
      if (!q.equals) {
        throw new Error("doesn't look like a proper Quad");
      }
      if (!q.subject.id || q.graph.id == null || q.predicate.id == null) {
        throw new Error(`corrupt patch: ${JSON.stringify(q)}`);
      }
      if (
        q.object.termType == "Literal" &&
        (q.object.datatypeString == "http://www.w3.org/2001/XMLSchema#float" || q.object.datatypeString == "http://www.w3.org/2001/XMLSchema#double")
      ) {
        throw new Error(`${JSON.stringify(q)} is using non-decimal for numbers, which is going to break some comparisons`);
      }
    });
  }

  matches(pat: QuadPattern): boolean {
    const allQuads = this.dels.concat(this.adds);
    return allQuads.some((quad) => {
      return (
        (pat.subject === null || pat.subject.equals(quad.subject)) && //
        (pat.predicate === null || pat.predicate.equals(quad.predicate)) && //
        (pat.object === null || pat.object.equals(quad.object)) && //
        (pat.graph === null || pat.graph.equals(quad.graph))
      );
    });
  }

  isEmpty() {
    return Immutable.is(this.dels, this.adds);
  }

  applyToGraph(g: N3.Store) {
    for (let quad of this.dels) {
      g.removeQuad(quad);
    }
    for (let quad of this.adds) {
      g.addQuad(quad);
    }
  }

  update(other: Patch): Patch {
    // this is approx, since it doesnt handle cancelling existing quads.
    return new Patch(this.dels.union(other.dels), this.adds.union(other.adds));
  }

  summary(): string {
    return "-" + this.dels.size + " +" + this.adds.size;
  }

  dump(): string {
    if (this.dels.size + this.adds.size > 20) {
      return this.summary();
    }
    const lines: string[] = [];
    const s = (term: N3.Term): string => {
      if (term.termType == "Literal") return term.value;
      if (term.termType == "NamedNode")
        return term.value
          .replace("http://light9.bigasterisk.com/effect/", "effect:")
          .replace("http://light9.bigasterisk.com/", ":")
          .replace("http://www.w3.org/2000/01/rdf-schema#", "rdfs:")
          .replace("http://www.w3.org/1999/02/22-rdf-syntax-ns#", "rdf:");
      if (term.termType == "BlankNode") return "_:" + term.value;
      return term.id;
    };
    const delPrefix = "- ",
      addPrefix = "\u200B+ "; // dels to sort before adds
    this.dels.forEach((d) => lines.push(delPrefix + s(d.subject) + " " + s(d.predicate) + " " + s(d.object)));
    this.adds.forEach((d) => lines.push(addPrefix + s(d.subject) + " " + s(d.predicate) + " " + s(d.object)));
    lines.sort();
    return lines.join("\n") + "\n" + (this.isEmpty() ? "(empty)" : "(nonempty)");
  }

  async toJsonPatch(): Promise<string> {
    return new Promise((res, rej) => {
      const out: SyncgraphPatchMessage = { patch: { adds: "", deletes: "" } };

      const writeDels = (cb1: () => void) => {
        const writer = new Writer({ format: "N-Quads" });
        writer.addQuads(this.dels.toArray());
        writer.end(function (err: any, result: string) {
          out.patch.deletes = result;
          cb1();
        });
      };

      const writeAdds = (cb2: () => void) => {
        const writer = new Writer({ format: "N-Quads" });
        writer.addQuads(this.adds.toArray());
        writer.end(function (err: any, result: string) {
          out.patch.adds = result;
          cb2();
        });
      };

      async.parallel([writeDels, writeAdds], (err: any) => res(JSON.stringify(out)));
    });
  }

  containsAnyPreds(preds: Iterable<NamedNode>): boolean {
    if (this._allPredsCache === undefined) {
      this._allPredsCache = Immutable.Set();
      this._allPredsCache.withMutations((cache) => {
        for (let qq of [this.adds, this.dels]) {
          for (let q of Array.from(qq)) {
            cache.add(q.predicate.value);
          }
        }
      });
    }

    for (let p of preds) {
      if (this._allPredsCache.has(p.value)) {
        return true;
      }
    }
    return false;
  }

  allSubjs(): Immutable.Set<string> {
    // returns subjs as Set of strings
    if (this._allSubjsCache === undefined) {
      this._allSubjsCache = Immutable.Set();
      this._allSubjsCache.withMutations((cache) => {
        for (let qq of [this.adds, this.dels]) {
          for (let q of Array.from(qq)) {
            cache.add(q.subject.value);
          }
        }
      });
    }

    return this._allSubjsCache;
  }

  allPreds(): Immutable.Set<NamedNode> {
    // todo: this could cache
    const ret = Immutable.Set<NamedNode>();
    ret.withMutations((r) => {
      for (let qq of [this.adds, this.dels]) {
        for (let q of Array.from(qq)) {
          if (q.predicate.termType == "Variable") throw "unsupported";
          r.add(q.predicate);
        }
      }
    });
    return ret;
  }
}

// The schema of the json sent from graph server.
export interface SyncgraphPatchMessage {
  patch: { adds: string; deletes: string };
}

export function patchToDeleteEntireGraph(g: N3.Store) {
  return new Patch(g.getQuads(null, null, null, null), []);
}

export function parseJsonPatch(input: SyncgraphPatchMessage, cb: (p: Patch) => void): void {
  // note response cb doesn't have an error arg.
  const dels: Quad[] = [];
  const adds: Quad[] = [];

  const parseAdds = (cb2: () => any) => {
    const parser = new Parser();
    return parser.parse(input.patch.adds, (error: any, quad: Quad, prefixes: any) => {
      if (quad) {
        return adds.push(quad);
      } else {
        return cb2();
      }
    });
  };
  const parseDels = (cb3: () => any) => {
    const parser = new Parser();
    return parser.parse(input.patch.deletes, (error: any, quad: any, prefixes: any) => {
      if (quad) {
        return dels.push(quad);
      } else {
        return cb3();
      }
    });
  };

  // todo: is it faster to run them in series? might be
  async.parallel([parseAdds, parseDels], (err: any) => cb(new Patch(dels, adds)));
}