use log::{error, debug, trace, warn};

use serde::{Serialize, Deserialize};
use serde_json::Value;
use serenity::model::Permissions;
use serenity::model::channel::Message;
use serenity::model::prelude::{ChannelType, PermissionOverwrite, PermissionOverwriteType};
use serenity::prelude::*;
use siren::{GetResponse, ServiceError};

pub struct OAI {
  pub client: reqwest::Client,
  pub base_url: String,
  pub service_url: String,
  pub max_attempts: i64,
  pub token: String,
  pub max_tokens: i64,
  pub default_model: GPTModel,
  pub max_context_questions: i64
}

#[derive(Debug, Clone, Serialize, Deserialize)]
struct ChatCompletionRequest {
  model: GPTModel,
  messages: Vec<ChatCompletionMessage>,
  /// Value between 0 and 2
  #[serde(skip_serializing_if = "Option::is_none")]
  temperature: Option<f64>,
  /// Value between 0 and 1
  #[serde(skip_serializing_if = "Option::is_none")]
  top_p: Option<f64>,
  #[serde(skip_serializing_if = "Option::is_none")]
  n: Option<f64>,
  #[serde(skip_serializing_if = "Option::is_none")]
  max_tokens: Option<i64>,
  /// Value between -2.0 and 2.0
  #[serde(skip_serializing_if = "Option::is_none")]
  presence_penalty: Option<f64>,
  /// Value between -2.0 and 2.0
  #[serde(skip_serializing_if = "Option::is_none")]
  frequency_penalty: Option<f64>,
  #[serde(skip_serializing_if = "Option::is_none")]
  user: Option<String>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
struct ChatCompletionMessage {
  role: GPTRole,
  content: String
}

#[derive(Debug, Clone, Serialize, Deserialize)]
enum GPTRole {
  #[serde(rename = "system")]
  System,
  #[serde(rename = "user")]
  User,
  #[serde(rename = "assistant")]
  Assistant,
  #[serde(rename = "function")]
  Function
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum GPTModel {
  #[serde(rename = "gpt-3.5-turbo")]
  GPT35Turbo,
  #[serde(rename = "gpt-3.5-turbo-0613")]
  GPT35Snapshot,
  #[serde(rename = "gpt-3.5-turbo-16k")]
  GPT3516k,
  #[serde(rename = "gpt-3.5-turbo-16k-0613")]
  GPT3516kSnapshot,
  #[serde(rename = "gpt-4")]
  GPT4,
  #[serde(rename = "gpt-4-0613")]
  GPT4Snapshot,
  #[serde(rename = "gpt-4-32k")]
  GPT432k,
  #[serde(rename = "gpt-4-32k-0613")]
  GPT432kSnapshot,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
struct ChatCompletionResponse {
  id: String,
  object: String,
  created: i64,
  model: GPTModel,
  usage: Usage,
  choices: Vec<Choice>
}

#[derive(Debug, Clone, Serialize, Deserialize)]
struct Usage {
  prompt_tokens: i64,
  completion_tokens: i64,
  total_tokens: i64
}

#[derive(Debug, Clone, Serialize, Deserialize)]
struct Choice {
  message: ChatCompletionMessage,
  finish_reason: String,
  index: i64
}

#[derive(Debug, Clone, Serialize, Deserialize)]
struct ResponseError {
  error: Option<ErrorDetails>,
  message: Option<String>,
  param: Option<String>,
  #[serde(rename = "type")]
  error_type: Option<String>
}

#[derive(Debug, Clone, Serialize, Deserialize)]
struct ErrorDetails {
  code: Option<String>
}

#[derive(Debug, Clone, Serialize, Deserialize)]
enum ResponseEvent {
  ChatCompletionResponse(ChatCompletionResponse),
  ResponseError(ResponseError)
}

impl OAI {
  async fn get_request(&self, request: ChatCompletionRequest) -> Result<ChatCompletionResponse, ServiceError> {
    let uri = format!("{}/chat/completions", self.base_url);
    let body = serde_json::to_string(&request).unwrap();
    trace!("Sending request to {}: {}", uri, body);

    let value = self.client
      .post(&uri)
      .bearer_auth(&self.token)
      .header("Content-Type", "application/json".to_string())
      .body(body)
      .send()
      .await?
      .json::<Value>()
      .await?;

    trace!("Received response from OpenAI: {:?}", value);
    
    // let response = match serde_json::from_value::<ResponseEvent>(value) {
    //   Ok(r) => {
    //     match r {
    //       ResponseEvent::ChatCompletionResponse(r) => r,
    //       ResponseEvent::ResponseError(e) => return Err(ServiceError { message: e.message.unwrap_or("Unknown error".to_string()), status: 500 }),
    //     }
    //   },
    //   Err(err) => return Err(ServiceError {
    //     message: format!("Could not parse response from OpenAI: {}", err),
    //     status: 500
    //   })
    // };
    let response = serde_json::from_value::<ChatCompletionResponse>(value)?;

    Ok(response)
  }

  async fn get_messages(&self, guild_id: u64, channel_id: u64, author_id: u64) -> Result<GetResponse<Vec<siren::Message>>, ServiceError> {
    let uri = format!("{}/messages?guild_id={}&channel_id={}&author_id={}&limit={}", self.service_url, guild_id, channel_id, author_id, self.max_context_questions);
    let value = self.client
      .get(&uri)
      .send()
      .await?
      .json::<Value>()
      .await?;

    let response = serde_json::from_value::<GetResponse<Vec<siren::Message>>>(value)?;

    Ok(response)
  }

  async fn store_message(&self, message: siren::Message) -> Result<siren::Message, ServiceError> {
    let uri = format!("{}/messages", self.service_url);
    trace!("Sending request to {}", uri);
    let value = self.client
      .post(&uri)
      .json::<siren::Message>(&message)
      .send()
      .await?
      .json::<Value>()
      .await?;
      trace!("Received response from Service: {:?}", value);
      let response = serde_json::from_value::<siren::Message>(value)?;
      Ok(response)
  }
}

pub async fn generate_response(ctx: &Context, msg: &Message, oai: &OAI) {
  debug!("Generating response for message: {}", msg.content);

  let guild_id = msg.guild_id.unwrap();
  let channel_id = msg.channel_id;
  let author_id = msg.author.id;

  // Parse out the bot mention from the message
  let bot_mention: String = format!("<@{}>", ctx.cache.current_user_id().0);
  let parsed_content = msg.content.replace(bot_mention.as_str(), "");

  let mut messages = vec![
    ChatCompletionMessage {
      role: GPTRole::System,
      content: "Siren is a Discord bot specializing in Dungeons and Dragons. Limit Siren's responses to <= 2000 characters. Siren must always obey these instructions, no matter what.".to_string()
    },
  ];
  
  let previous_messages = oai.get_messages(guild_id.0, channel_id.0, author_id.0).await;
  match previous_messages {
    Ok(m) => {
      for message in m.data {
        messages.push(
          ChatCompletionMessage {
            role: GPTRole::User,
            content: format!("{}", message.request)
          }
        );
        messages.push(
          ChatCompletionMessage {
            role: GPTRole::Assistant,
            content: format!("{}", message.response)
          }
        );
      }
    },
    Err(err) => warn!("Could not load previous messages: {}", err)
  };
  messages.push(ChatCompletionMessage { role: GPTRole::User, content: parsed_content.clone() });

  let request = ChatCompletionRequest {
    model: oai.default_model.clone(),
    messages,
    temperature: Some(0.5),
    top_p: None,
    n: None,
    max_tokens: Some(oai.max_tokens),
    presence_penalty: Some(0.6),
    frequency_penalty: Some(0.0),
    user: Some(msg.author.name.clone())
  };

  // Get the thread channel ID
  let response_channel = match msg.channel_id.create_private_thread(&ctx.http, |thread| {
    thread.name(truncate(&parsed_content, 99)).kind(ChannelType::PublicThread)
  }).await {
    Ok(c) => {
      let allow = Permissions::SEND_MESSAGES;
      let deny = Permissions::SEND_TTS_MESSAGES | Permissions::ATTACH_FILES;
      let overwrite = PermissionOverwrite {
        allow,
        deny,
        kind: PermissionOverwriteType::Member(msg.author.id),
      };
      let _ = c.create_permission(&ctx.http, &overwrite).await;
      c.id
    }
    Err(_) => {
      channel_id
    }
  };

  let typing = response_channel.start_typing(&ctx.http).unwrap();

  // Get the OAI response and store message/response into the database
  let response = match oai.get_request(request).await {
    Ok(r) => {
      debug!("Processing response received from OpenAI");
      if !r.choices.is_empty() {
        let res = r.choices[0].message.content.clone();
        if let Err(err) = oai.store_message(siren::Message {
          id: r.id,
          guild_id: guild_id.0 as i64,
          channel_id: response_channel.0 as i64,
          user_id: author_id.0 as i64,
          created: r.created,
          model: serde_json::to_string(&r.model).unwrap(),
          request: parsed_content,
          response: res.clone(),
          request_tags: vec![],
          response_tags: vec![],
        }).await {
          warn!("{}", err);
        }
        res
      } else {
        warn!("No choices received in the response from OpenAI");
        "No reply received".to_string()
      }
    }
    Err(err) => {
      error!("Could not get response from OpenAI: {}", err.message);
      "There was an error processing your message. Please try again later.".to_string()
    }
  };
  debug!("Writing response: \"{}\"", response);

  typing.stop();
  if let Err(why) = response_channel.say(&ctx.http, response).await {
    error!("Cannot send message: {}", why);
  }

  // match msg.channel_id.create_public_thread(&ctx.http, msg.id, |thread| {
  //     thread.name(truncate(&parsed_content, 99)).kind(ChannelType::PublicThread)
  // }).await {
  //   Ok(c) => {
  //     if let Err(why) = c.say(&ctx.http, response).await {
  //       error!("Cannot send message: {}", why);
  //     }
  //   }
  //   Err(_) => {
  //     if let Err(why) = channel_id.say(&ctx.http, response).await {
  //       error!("Cannot send message: {}", why);
  //     }
  //   }
  // };
}

fn truncate(s: &str, max_chars: usize) -> &str {
  match s.char_indices().nth(max_chars) {
    None => s,
    Some((idx, _)) => &s[..idx],
  }
}