use crate::entities::{UserAuthResponse, UserWorkspace};
use base64::engine::general_purpose::STANDARD;
use base64::Engine;
use chrono::Utc;
use serde::de::{MapAccess, Visitor};
use serde::{Deserialize, Deserializer, Serialize};
use serde_json::Value;
use std::fmt;
use std::fmt::Display;
use uuid::Uuid;

#[derive(Debug, Clone, Serialize)]
pub struct Session {
  pub user_id: i64,
  pub user_uuid: Uuid,
  pub user_workspace: UserWorkspace,
}

impl Display for Session {
  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    write!(
      f,
      "user_id: {}, user_workspace: {}:{}",
      self.user_id, self.user_workspace.name, self.user_workspace.id,
    )
  }
}

struct SessionVisitor;
impl<'de> Visitor<'de> for SessionVisitor {
  type Value = Session;

  fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
    formatter.write_str("Session")
  }

  fn visit_map<M>(self, mut map: M) -> Result<Self::Value, M::Error>
  where
    M: MapAccess<'de>,
  {
    let mut user_id = None;
    let mut user_uuid = None;
    // For historical reasons, the session used to contain a workspace_id field.
    // This field is no longer used, and is replaced by user_workspace.
    let mut workspace_id = None;
    let mut user_workspace = None;

    while let Some(key) = map.next_key::<String>()? {
      match key.as_str() {
        "user_id" => {
          user_id = Some(map.next_value()?);
        },
        "user_uuid" => {
          user_uuid = Some(map.next_value()?);
        },
        "workspace_id" => {
          workspace_id = Some(map.next_value()?);
        },
        "user_workspace" => {
          user_workspace = Some(map.next_value()?);
        },
        _ => {
          let _ = map.next_value::<Value>();
        },
      }
    }
    let user_id = user_id.ok_or(serde::de::Error::missing_field("user_id"))?;
    let user_uuid = user_uuid.ok_or(serde::de::Error::missing_field("user_uuid"))?;
    if user_workspace.is_none() {
      if let Some(workspace_id) = workspace_id {
        user_workspace = Some(UserWorkspace {
          id: workspace_id,
          name: "My Workspace".to_string(),
          created_at: Utc::now(),
          // For historical reasons, the database_storage_id is constructed by the user_id.
          database_indexer_id: STANDARD.encode(format!("{}:user:database", user_id)),
          icon: "".to_owned(),
        })
      }
    }

    let session = Session {
      user_id,
      user_uuid,
      user_workspace: user_workspace.ok_or(serde::de::Error::missing_field("user_workspace"))?,
    };

    Ok(session)
  }
}

impl<'de> Deserialize<'de> for Session {
  fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
  where
    D: Deserializer<'de>,
  {
    deserializer.deserialize_any(SessionVisitor)
  }
}

impl<T> From<&T> for Session
where
  T: UserAuthResponse,
{
  fn from(value: &T) -> Self {
    Self {
      user_id: value.user_id(),
      user_uuid: *value.user_uuid(),
      user_workspace: value.latest_workspace().clone(),
    }
  }
}

impl std::convert::From<Session> for String {
  fn from(session: Session) -> Self {
    serde_json::to_string(&session).unwrap_or_else(|e| {
      tracing::error!("Serialize session to string failed: {:?}", e);
      "".to_string()
    })
  }
}