use std::time::{SystemTime, UNIX_EPOCH};

use poise::{serenity_prelude::{ChannelId, EditMessage, GetMessages, Http, Message, MessageId, UserId}, ReplyHandle};
use serde_json::{json, Map, Value};

use crate::{data::{self, get_mutex_data}, lang, messages::{edit_reply, embed_from_options, http_send_embed, make_post_embed, make_removed_embed, send_msg}, websocket::send_cmd_json, Context, Error, BK_WEEK};

#[poise::command(
  slash_command,
  prefix_command,
  rename = "re_updatediscord",
  category = "re",
  guild_only,
  guild_cooldown = 120,
  required_bot_permissions = "SEND_MESSAGES | VIEW_CHANNEL | READ_MESSAGE_HISTORY | EMBED_LINKS"
)]
/// Updates the binded Discord channel with the bot's current Reddit data.
pub async fn cmd(
  ctx: Context<'_>,
  #[description = "Only adds new posts, leaves everything else unchanged."]
    only_add: Option<bool>,
  #[description = "The max age of a post (in days). Any post older than this will be removed. (0 is infinite.)"]
  #[min = 0]
  #[max = 65535]
    max_age: Option<u16>
) -> Result<(), Error>
{
  let http = ctx.http();

  let mut p_text = "`/bk_week_update`:".to_string();

  let progress = send_msg(ctx, p_text.clone(), true, true).await.unwrap();
  p_text = update_progress(ctx, progress.clone(), p_text, "\nFetching new posts & updating data file...".to_string()).await;

  let max_age_u = max_age.unwrap_or(8);
  let max_age_secs = max_age_u as u64 * (60 * 60 * 24);

  send_cmd_json("add_new_posts", Some(json!([max_age_secs]))).await;
  data::update_re_data(ctx.data()).await;
  let r_data = get_mutex_data(&ctx.data().reddit_data).await?;

  let c_id_u = get_c_id(ctx).await;
  
  if c_id_u.is_none() {
    send_msg(ctx, "Could not find bk_week_channel in data!\nHint: Run (or tell an admin to run) `/bk_admin_bind` in a (preferably read-only) channel.".to_string(), true, true).await;
    return Ok(());
  }

  let c_id = c_id_u.unwrap();

  // Reading messages
  p_text = update_progress(ctx, progress.clone(), p_text.clone(), format!("✅\nReading messages in <#{}>...", c_id)).await;
  let msgs = read_msgs(http, ctx.framework().bot_id, c_id).await;

  // Parsing messages to JSON
  p_text = update_progress(ctx, progress.clone(), p_text.clone(), "✅\nParsing messages to JSON...".to_string()).await;
  let msgs_json = msgs_to_json(msgs, &r_data, max_age_secs).await;

  // Adding new posts 
  p_text = update_progress(ctx, progress.clone(), p_text.clone(), "✅\nAdding new posts...".to_string()).await;
  let weekly_art = r_data[BK_WEEK].as_object().unwrap();
  add_posts(http, c_id, weekly_art, &msgs_json, max_age_secs).await;
  
  // Stop if only_add
  if only_add.unwrap_or(false) {
    send_msg(ctx, "`/bk_week_update`\n## Done!".to_string(), true, true).await;
    update_progress(ctx, progress.clone(), p_text, "✅\n## Done!".to_string()).await;
    return Ok(());
  }

  // Editing updated posts
  p_text = update_progress(ctx, progress.clone(), p_text.clone(), "✅\nEditing updated posts...".to_string()).await;
  edit_posts(http, c_id, weekly_art, &msgs_json).await;

  // Removing removed posts
  p_text = update_progress(ctx, progress.clone(), p_text.clone(), "✅\nRemoving removed posts...".to_string()).await;
  remove_posts(http, c_id, weekly_art, &msgs_json).await;

  // Removing old posts
  if max_age_u > 0 {
    p_text = update_progress(ctx, progress.clone(), p_text.clone(), format!("✅\nRemoving old posts (threshold: {}d)...", max_age_u)).await;
    remove_old(http, c_id, &msgs_json).await;
    send_cmd_json("remove_old_posts", Some(json!([max_age_secs]))).await;
  }

  // Removing duplicate posts
  p_text = update_progress(ctx, progress.clone(), p_text.clone(), "✅\nRemoving duplicate posts...".to_string()).await;
  remove_dupes(http, c_id, &msgs_json).await;

  // Done
  update_progress(ctx, progress.clone(), p_text, "✅\n## Done!".to_string()).await;
  send_msg(ctx, "`/bk_week_update`\n## Done!".to_string(), true, true).await;

  return Ok(());
}


async fn update_progress(ctx: Context<'_>, p: ReplyHandle<'_>, t: String, added_t: String) -> String {
  let p_text = format!("{} {}", t, added_t);

  edit_reply(ctx, p, p_text.clone()).await;
  return p_text;
}


async fn get_c_id(ctx: Context<'_>) -> Option<ChannelId> {
  if !data::dc_contains_server(ctx.data(), ctx.guild_id().unwrap().into()).await {
    send_msg(ctx, lang!("dc_404"), false, false).await;
    return None;
  }

  let d = get_mutex_data(&ctx.data().discord_data).await.unwrap();
  let c_id_u =
    d["servers"]
     [ctx.guild_id().unwrap().to_string()]
     ["bk_week_channel"].as_u64().unwrap();

  let c_id = ChannelId::new(c_id_u);

  return Some(c_id);
}


async fn read_msgs(http: &Http, bot_id: UserId, c_id: ChannelId) -> Vec<Message> {
  let b = GetMessages::new().limit(100);
  let mut msgs = c_id.messages(http, b).await.unwrap();
  msgs.retain(|item| item.author.id == bot_id);

  let mut last_msg: Option<Message> = msgs.last().cloned();

  while last_msg.is_some() {
    let new_b = GetMessages::new().limit(100).before(last_msg.clone().unwrap());
    let new_msgs = c_id.messages(http, new_b).await.unwrap();

    last_msg = new_msgs.last().cloned();

    if new_msgs.is_empty() {
      break;
    }

    let filtered_msgs: Vec<Message> = new_msgs
      .into_iter()
      .filter(|item| item.author.id == bot_id)
      .collect();

    msgs.extend(filtered_msgs);
  }

  return msgs;
}


async fn msgs_to_json(msgs: Vec<Message>, reddit_data: &Value, max_age: u64) -> Value {
  let mut msgs_json: Value = json!({"no_change": {}, "updated": {}, "removed": {}, "duplicates": {}, "old": {}});
  let now = SystemTime::now()
    .duration_since(UNIX_EPOCH)
    .expect("Time went backwards")
    .as_secs();

  for msg in msgs {
    if msg.embeds.is_empty() { continue; }
    if msg.embeds[0].url.is_none() { continue; }

    let url = msg.embeds[0].url.clone().unwrap();
    
    // duplicates
    if ["no_change", "updated", "removed", "old"]
      .iter()
      .any(|key| msgs_json[key].as_object().unwrap().contains_key(&url))
    {
      let dupes_mut = msgs_json["duplicates"].as_object_mut().unwrap();
      if !dupes_mut.contains_key(&url) { 
        dupes_mut.insert(url.clone(), json!(msg.id.get()));
      }
      continue;
    }

    let msg_desc = &msg.embeds[0].description.clone().unwrap();
    let msg_lines = msg_desc.split("\n");
    let msg_last_len = msg_lines.clone().last().unwrap().len();

    if msg_last_len < 13 { continue; }

    let msg_json_str = &msg_lines.clone().last().unwrap()[9..msg_last_len - 3];
    
    let msg_json = serde_json::from_str(msg_json_str);
    if msg_json.is_err() { continue; }

    let mut u_json: Value = msg_json.unwrap();
    let re_url = &reddit_data[BK_WEEK][&url];

    let post_date = re_url["post_data"]["date_unix"].as_u64().unwrap_or(0);

    // old
    if now - post_date > max_age {
      if let Some(obj) = msgs_json["old"].as_object_mut() {
        obj.insert(url.clone(), json!(msg.id.get()));
        continue;
      }
    }

    // removed
    if re_url.get("removed").is_some() {
      if u_json.get("removed").is_some() {
        // no change
        if let Some(obj) = msgs_json["no_change"].as_object_mut() {
          obj.insert(url.clone(), json!(msg.id.get()));
          continue;
        }
      }

      // removed
      if let Some(obj) = msgs_json["removed"].as_object_mut() {
        obj.insert(url.clone(), json!(msg.id.get()));
        continue;
      }
    }

    // updated
    if u_json["added"]                != re_url["added"]
    || u_json["approved"]             != re_url["approved"]
    || u_json["post_data"]["upvotes"] != re_url["post_data"]["upvotes"]
    || u_json["votes"]["mod_voters"]  != re_url["votes"]["mod_voters"]
    {
      u_json.as_object_mut().unwrap().insert("msg_id".to_string(), Value::String(msg.id.clone().to_string()));

      if let Some(obj) = msgs_json["updated"].as_object_mut() {
        obj.insert(url.clone(), json!(msg.id.get()));
        continue;
      }
    }

    // no change
    if let Some(obj) = msgs_json["no_change"].as_object_mut() {
      obj.insert(url.clone(), json!(msg.id.get()));
    }
  }

  return msgs_json;
}


async fn add_posts(http: &Http, c_id: ChannelId, r_data: &Map<String, Value>, msgs_json: &Value, max_age: u64) {
  let now = SystemTime::now()
    .duration_since(UNIX_EPOCH)
    .expect("Time went backwards")
    .as_secs();

  for url in r_data.keys() {
    if ["no_change", "updated", "removed", "old", "duplicates"]
      .iter()
      .any(|key| msgs_json[key].as_object().unwrap().contains_key(url))
      { continue; }

    let post_date = r_data[url]["post_data"]["date_unix"].as_u64().unwrap();
    if now - post_date > max_age { continue; }

    if r_data[url].get("removed").is_some() {
      http_send_embed(http, c_id, make_removed_embed(&r_data[url], url, false)).await;
      continue;
    }

    http_send_embed(http, c_id, make_post_embed(&r_data[url], url, false)).await;
  }
}


async fn edit_posts(http: &Http, c_id: ChannelId, r_data: &Map<String, Value>, msgs_json: &Value) {
  for (url, msg_id) in msgs_json["updated"].as_object().unwrap() {
    let mut msg = http.get_message(c_id, MessageId::new(msg_id.as_u64().unwrap())).await.unwrap();
    let r = EditMessage::new()
      .embeds(vec![embed_from_options(make_post_embed(&r_data[url], url, false))]);
  
    let _ = msg.edit(http, r).await;
  }
}


async fn remove_posts(http: &Http, c_id: ChannelId, r_data: &Map<String, Value>, msgs_json: &Value) {
  for (url, msg_id) in msgs_json["removed"].as_object().unwrap() {
    let mut msg = http.get_message(c_id, MessageId::new(msg_id.as_u64().unwrap())).await.unwrap();
    let r = EditMessage::new()
      .embeds(vec![embed_from_options(make_removed_embed(&r_data[url], url, false))]);
  
    let _ = msg.edit(http, r).await;
  }
}


async fn remove_old(http: &Http, c_id: ChannelId, msgs_json: &Value) {
  for (_url, msg_id) in msgs_json["old"].as_object().unwrap() {
    let msg = http.get_message(c_id, MessageId::new(msg_id.as_u64().unwrap())).await.unwrap();
    let _ = msg.delete(http).await;
  }
}


async fn remove_dupes(http: &Http, c_id: ChannelId, msgs_json: &Value) {
  for (_url, msgs) in msgs_json["duplicates"].as_object().unwrap() {
    for msg_id in msgs.as_array().unwrap() {
      let msg = http.get_message(c_id, MessageId::new(msg_id.as_u64().unwrap())).await.unwrap();
      let _ = msg.delete(http).await;
    }
  }
}