module ap.activity_stream;

import std.algorithm;
import std.array;
import std.datetime;
import std.format;
import std.json;

import util;

union Store {
  string str;
  ASObject[] array;
  Link[] links;
}

enum ObjectType {
  Object,
  String,
  Array,
}

/++ 
 * Basic ActivityStream Object
 * https://www.w3.org/TR/activitypub/#obj
 +/
class ASObject {
  // Required fields (for root objects)
  JSONValue context; /// Must be activitystream context
  string id; /// AP requirement for unique identifier
  string type; /// AP requirement for type of object

  // Optional fields
  ASObject attachment;
  ASObject attributedTo;
  ASObject audience;
  string content;
  string name;
  DateTime endTime;
  ASObject generator;
  ASObject icon;
  ASObject image;
  ASObject inReplyTo;
  ASObject location;
  ASObject preview;
  DateTime published;
  Collection replies;
  DateTime startTime;
  string summary;
  ASObject tag;
  DateTime updated;
  Link url;
  ASObject to;
  ASObject bto;
  ASObject cc;
  ASObject bcc;
  string mediaType;
  string duration;

  JSONValue raw;

  protected Store m_store;
  protected ObjectType m_objType;

  this() {
  }

  /++ 
   + Constructs the object according to json source
   + Params:
   +   json = the source json
   + Returns: Object
   +/
  this(JSONValue json) {
    switch (json.type) {
    case JSONType.ARRAY:
      this.m_objType = ObjectType.Array;
      this.m_store.array = json.array.map!(item => new ASObject(item)).array;
      break;

    case JSONType.OBJECT:
      this.m_objType = ObjectType.Object;

      // String properties
      optional(json, "context", context);
      optional(json, "id", id);
      optional(json, "type", type);
      optional(json, "content", content);
      optional(json, "name", name);
      optional(json, "summary", summary);
      optional(json, "mediaType", mediaType);
      optional(json, "duration", duration);

      // AS Object properties
      generator = new ASObject(json.optional!JSONValue("generator"));
      icon = new ASObject(json.optional!JSONValue("icon"));
      image = new ASObject(json.optional!JSONValue("image"));
      inReplyTo = new ASObject(json.optional!JSONValue("inReplyTo"));
      location = new ASObject(json.optional!JSONValue("location"));
      preview = new ASObject(json.optional!JSONValue("preview"));
      tag = new ASObject(json.optional!JSONValue("tag"));
      to = new ASObject(json.optional!JSONValue("to"));
      bto = new ASObject(json.optional!JSONValue("bto"));
      cc = new ASObject(json.optional!JSONValue("cc"));
      bcc = new ASObject(json.optional!JSONValue("bcc"));

      const(JSONValue)* j;

      // Date properties
      // if ((j = "endTime" in json) != null)
      //   endTime = DateTime.fromISOString(json["endTime"].str);

      // if ((j = "published" in json) != null)
      //   published = DateTime.fromISOString(json["published"].str);

      // if ((j = "startTime" in json) != null)
      //   startTime = DateTime.fromISOString(json["startTime"].str);

      // if ((j = "updated" in json) != null)
      //   updated = DateTime.fromISOString(json["updated"].str);

      url = new Link(json.optional!JSONValue("url"));

      break;

    case JSONType.STRING:
      this.m_objType = ObjectType.String;
      this.m_store.str = json.str;
      break;

    case JSONType.NULL:
      break;

    default:
      throw new Exception("Unrecognized ActivityStream Object JSON format: " ~ json.type);
    }

    raw = json;
  }

  string stringRep(int indentation = 0, string indentStr = "  ") const {
    string[] output;
    string indent = "";
    string j;

    if (this.m_objType == ObjectType.String)
      return format("%s%s\n", indent, this.m_store.str);

    if (this.m_objType == ObjectType.Array) {
      output ~= "[";

      foreach (obj; this.m_store.array)
        output ~= format("%s%s%s%s,", indent, indentStr, indentStr, obj.stringRep(indentation + 1));

      output ~= format("%s%s]", indent, indentStr);

      return output.length == 2 ? "" : output.join("\n");
    }

    for (int i = 0; i < indentation; i++)
      indent ~= indentStr;

    output ~= format("%s {", this.type);

    if (id)
      output ~= format("%s%sid = %s", indent, indentStr, id);

    if (content)
      output ~= format("%s%scontent = %s", indent, indentStr, content);

    if (name)
      output ~= format("%s%sname = %s", indent, indentStr, name);

    // if (summary)
    //   output ~= format("%s%ssummary = %s", indent, indentStr, summary);

    if (mediaType)
      output ~= format("%s%smediaType = %s", indent, indentStr, mediaType);

    if (duration)
      output ~= format("%s%sduration = %s", indent, indentStr, duration);

    if (url && (j = url.stringRep(indentation + 1)) != string.init)
      output ~= format("%s%surl = %s", indent, indentStr, j);

    if (icon && (j = icon.stringRep(indentation + 1)) != string.init)
      output ~= format("%s%sicon = %s", indent, indentStr, j);

    if (image && (j = image.stringRep(indentation + 1)) != string.init)
      output ~= format("%s%simage = %s", indent, indentStr, j);

    if (tag && (j = tag.stringRep(indentation + 1)) != string.init)
      output ~= format("%s%stag = %s", indent, indentStr, j);

    output ~= indent ~ "}";

    return output.length == 2 ? "" : output.join("\n");
  }
}

class Link {
  string type;
  string href;
  string[] rel;
  string mediaType;
  string name;
  int height, width;
  ASObject preview;

  protected Store m_store;
  protected ObjectType m_objType;

  JSONValue raw;

  this() {
  }

  this(JSONValue json) {
    switch (json.type) {
    case JSONType.ARRAY:
      m_objType = ObjectType.Array;
      m_store.links = json.array.map!(item => new Link(item)).array;
      break;

    case JSONType.OBJECT:
      m_objType = ObjectType.Object;

      optional(json, "type", type);
      optional(json, "href", href);
      optional(json, "mediaType", mediaType);
      optional(json, "name", name);
      optional(json, "height", height);
      optional(json, "width", width);

      const(JSONValue)* j;
      if ((j = "rel" in json) != null)
        rel = (*j).array.map!(item => item.str).array;

      preview = new ASObject(json.optional!JSONValue("preview"));
      break;

    case JSONType.STRING:
      m_objType = ObjectType.String;
      m_store.str = json.str;
      break;

    case JSONType.NULL:
      break;

    default:
      throw new Exception("Unrecognized ActivityStream Link JSON format");
    }

    this.raw = json;
  }

  string stringRep(int indentation = 0, string indentStr = "  ") const {
    string[] output;
    string indent = "";
    string j;

    if (this.m_objType == ObjectType.String)
      return format("%s%s", indent, this.m_store.str);

    for (int i = 0; i < indentation; i++)
      indent ~= indentStr;

    output ~= format("%s {", this.type);

    if (href)
      output ~= format("%s%shref = %s", indent, indentStr, href);

    if (mediaType)
      output ~= format("%s%smediaType = %s", indent, indentStr, mediaType);

    if (name)
      output ~= format("%s%sname = %s", indent, indentStr, name);

    if (height)
      output ~= format("%s%sheight = %d", indent, indentStr, height);

    if (width)
      output ~= format("%s%swidth = %d", indent, indentStr, width);

    if (preview && (j = preview.stringRep(indentation + 1)) != string.init)
      output ~= format("%s%spreview = %s", indent, indentStr, j);

    output ~= indent ~ "}";

    if (output.length == 2)
      return "";

    return output.join("\n");
  }
}

class Collection : ASObject {
  int totalItems;
  CollectionPage current;
  CollectionPage first;
  CollectionPage last;
  ASObject items;

  this(JSONValue json) {
    super(json);

    if (this.m_objType != ObjectType.Object)
      throw new Exception("Wrong Collection format?");

    optional(json, "totalItems", totalItems);
    current = new CollectionPage(json.optional!JSONValue("current"));
    first = new CollectionPage(json.optional!JSONValue("first"));
    last = new CollectionPage(json.optional!JSONValue("last"));
    items = new ASObject(json.optional!JSONValue("items"));
  }
}

class CollectionPage : Collection {
  CollectionPage partOf;
  CollectionPage next;
  CollectionPage prev;

  this(JSONValue json) {
    super(json);

    if (this.m_objType != ObjectType.Object)
      throw new Exception("Wrong CollectionPage format?");

    partOf = new CollectionPage(json.optional!JSONValue("partOf"));
    next = new CollectionPage(json.optional!JSONValue("next"));
    prev = new CollectionPage(json.optional!JSONValue("prev"));
  }
}