//! Message types and conversion methods for `golgi`.

use kuska_ssb::api::dto::content::TypedMessage;
use serde::{Deserialize, Serialize};
use serde_json::Value;
use std::fmt::Debug;

use crate::error::GolgiError;

/// This is an alias to TypedMessage in kuska,
/// which is renamed as SsbMessageContent in golgi to fit the naming convention
/// of the other types (SsbMessageKVT and SsbMessageValue)
pub type SsbMessageContent = TypedMessage;

/// Data type representing the `value` of a message object (`KVT`). More information concerning the
/// data model can be found
/// in the [`Metadata` documentation](https://spec.scuttlebutt.nz/feed/messages.html#metadata).
#[derive(Serialize, Deserialize, Debug)]
#[serde(deny_unknown_fields)]
#[allow(missing_docs)]
pub struct SsbMessageValue {
    pub previous: Option<String>,
    pub author: String,
    pub sequence: u64,
    pub timestamp: f64,
    pub hash: String,
    pub content: Value,
    pub signature: String,
}

// Enum representing the different possible message content types
#[derive(Debug)]
#[allow(missing_docs)]
pub enum SsbMessageContentType {
    About,
    Vote,
    Post,
    Contact,
    Unrecognized,
}

impl SsbMessageValue {
    /// Gets the type field of the message content as an enum, if found.
    /// if no type field is found or the type field is not a string, it returns an Err(GolgiError::ContentType)
    /// if a type field is found but with an unknown string it returns an Ok(SsbMessageContentType::Unrecognized)
    pub fn get_message_type(&self) -> Result<SsbMessageContentType, GolgiError> {
        let msg_type = self
            .content
            .get("type")
            .ok_or_else(|| GolgiError::ContentType("type field not found".to_string()))?;
        let mtype_str: &str = msg_type.as_str().ok_or_else(|| {
            GolgiError::ContentType("type field value is not a string as expected".to_string())
        })?;
        let enum_type = match mtype_str {
            "about" => SsbMessageContentType::About,
            "post" => SsbMessageContentType::Post,
            "vote" => SsbMessageContentType::Vote,
            "contact" => SsbMessageContentType::Contact,
            _ => SsbMessageContentType::Unrecognized,
        };
        Ok(enum_type)
    }

    /// Helper function which returns true if this message is of the given type,
    /// and false if the type does not match or is not found
    pub fn is_message_type(&self, message_type: SsbMessageContentType) -> bool {
        let self_message_type = self.get_message_type();
        match self_message_type {
            Ok(mtype) => {
                matches!(mtype, message_type)
            }
            Err(_err) => false,
        }
    }

    /// Converts the content json value into an SsbMessageContent enum,
    /// using the "type" field as a tag to select which variant of the enum
    /// to deserialize into.
    ///
    /// See more info on this here https://serde.rs/enum-representations.html#internally-tagged
    pub fn into_ssb_message_content(self) -> Result<SsbMessageContent, GolgiError> {
        let m: SsbMessageContent = serde_json::from_value(self.content)?;
        Ok(m)
    }
}

/// Data type representing the `value` of a message object (`KVT`). More information concerning the
/// data model can be found
/// in the [`Metadata` documentation](https://spec.scuttlebutt.nz/feed/messages.html#metadata).
#[derive(Serialize, Deserialize, Debug)]
#[serde(deny_unknown_fields)]
#[allow(missing_docs)]
pub struct SsbMessageKVT {
    pub key: String,
    pub value: SsbMessageValue,
    pub timestamp: f64,
    pub rts: Option<f64>,
}