use serde::{Deserialize, Serialize};
use std::fmt;
use std::str::FromStr;
use uuid::Uuid;

pub const HEADER_X_CORRELATION_ID: &str = "x-correlation-id";
pub const HEADER_TRACEPARENT: &str = "traceparent";
pub const HEADER_TRACE_ID: &str = "trace-id";
pub const NATS_HEADER_CORRELATION_ID: &str = "correlation-id";

#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize, Default)]
pub struct TenantId(String);

impl TenantId {
    pub fn new(id: impl Into<String>) -> Self {
        Self(id.into())
    }

    pub fn is_empty(&self) -> bool {
        self.0.is_empty()
    }

    pub fn as_str(&self) -> &str {
        &self.0
    }
}

impl fmt::Display for TenantId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}", self.0)
    }
}

impl FromStr for TenantId {
    type Err = std::convert::Infallible;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        Ok(Self(s.to_string()))
    }
}

impl AsRef<str> for TenantId {
    fn as_ref(&self) -> &str {
        &self.0
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(transparent)]
pub struct CorrelationId(String);

impl CorrelationId {
    pub fn new(id: impl Into<String>) -> Self {
        Self(id.into())
    }

    pub fn generate() -> Self {
        Self(Uuid::new_v4().to_string())
    }

    pub fn as_str(&self) -> &str {
        &self.0
    }
}

impl fmt::Display for CorrelationId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}", self.0)
    }
}

impl FromStr for CorrelationId {
    type Err = std::convert::Infallible;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        Ok(Self(s.to_string()))
    }
}

impl AsRef<str> for CorrelationId {
    fn as_ref(&self) -> &str {
        &self.0
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(transparent)]
pub struct TraceId(String);

impl TraceId {
    pub fn new(id: impl Into<String>) -> Self {
        Self(id.into())
    }

    pub fn as_str(&self) -> &str {
        &self.0
    }

    pub fn is_valid_hex_32(&self) -> bool {
        is_valid_hex_32(self.as_str())
    }
}

impl fmt::Display for TraceId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}", self.0)
    }
}

impl FromStr for TraceId {
    type Err = std::convert::Infallible;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        Ok(Self(s.to_string()))
    }
}

impl AsRef<str> for TraceId {
    fn as_ref(&self) -> &str {
        &self.0
    }
}

pub fn trace_id_from_traceparent(traceparent: &str) -> Option<&str> {
    let mut parts = traceparent.split('-');
    let version = parts.next()?;
    let trace_id = parts.next()?;
    let span_id = parts.next()?;
    let flags = parts.next()?;
    if version.len() != 2 || trace_id.len() != 32 || span_id.len() != 16 || flags.len() != 2 {
        return None;
    }
    if !trace_id.chars().all(|c| c.is_ascii_hexdigit())
        || !span_id.chars().all(|c| c.is_ascii_hexdigit())
        || !flags.chars().all(|c| c.is_ascii_hexdigit())
        || !version.chars().all(|c| c.is_ascii_hexdigit())
    {
        return None;
    }
    Some(trace_id)
}

pub fn traceparent_from_trace_id(trace_id: &TraceId) -> Option<String> {
    if !trace_id.is_valid_hex_32() {
        return None;
    }
    let span_id = Uuid::new_v4().simple().to_string()[..16].to_string();
    Some(format!("00-{}-{span_id}-01", trace_id.as_str()))
}

fn is_valid_hex_32(s: &str) -> bool {
    s.len() == 32 && s.chars().all(|c| c.is_ascii_hexdigit())
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn tenant_id_serialization_roundtrip() {
        let id = TenantId::new("acme-corp");
        let json = serde_json::to_string(&id).unwrap();
        let decoded: TenantId = serde_json::from_str(&json).unwrap();
        assert_eq!(id, decoded);
    }

    #[test]
    fn tenant_id_default_is_empty() {
        let id = TenantId::default();
        assert!(id.is_empty());
    }

    #[test]
    fn tenant_id_is_send_sync() {
        fn assert_send_sync<T: Send + Sync>() {}
        assert_send_sync::<TenantId>();
    }

    #[test]
    fn correlation_id_roundtrip_is_string() {
        let id = CorrelationId::new("corr-1");
        let json = serde_json::to_string(&id).unwrap();
        assert_eq!(json, "\"corr-1\"");
        let decoded: CorrelationId = serde_json::from_str(&json).unwrap();
        assert_eq!(decoded.as_str(), "corr-1");
    }

    #[test]
    fn trace_id_from_traceparent_parses() {
        let tp = "00-0123456789abcdef0123456789abcdef-1111111111111111-01";
        assert_eq!(
            trace_id_from_traceparent(tp),
            Some("0123456789abcdef0123456789abcdef")
        );
    }
}