//! `TriggerEvent` — the description of the event that fired a script.
//!
//! Built by the dispatcher (in `manager-core`) from the outbox row and
//! attached to the `ExecRequest` that's handed to `executor-core`. The
//! Rhai bridge in `executor-core::engine::build_ctx_map` flattens this
//! into `ctx.event` for the script.
//!
//! Living in `picloud-shared` so the dispatcher and the executor agree
//! on the wire shape. Serializable so cluster mode (v1.3+) can ship
//! ExecRequests over HTTP without rewriting this type.

use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};

use crate::{DeadLetterId, ScriptId, TriggerId};

/// Operations a KV trigger can fire on. Stored as a lowercase string
/// in `kv_trigger_details.ops` (Postgres `text[]`).
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(rename_all = "lowercase")]
pub enum KvEventOp {
    Insert,
    Update,
    Delete,
}

impl KvEventOp {
    #[must_use]
    pub const fn as_str(self) -> &'static str {
        match self {
            Self::Insert => "insert",
            Self::Update => "update",
            Self::Delete => "delete",
        }
    }

    #[must_use]
    pub fn from_wire(s: &str) -> Option<Self> {
        match s {
            "insert" => Some(Self::Insert),
            "update" => Some(Self::Update),
            "delete" => Some(Self::Delete),
            _ => None,
        }
    }
}

/// Discriminated description of a triggering event. Lifted from the
/// outbox row's payload at dispatch time. Each variant carries the
/// fields the corresponding `ctx.event` shape exposes to the script.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(tag = "source", rename_all = "snake_case")]
pub enum TriggerEvent {
    /// A KV insert / update / delete fired this handler.
    Kv {
        op: KvEventOp,
        collection: String,
        key: String,
        /// Present on `insert` and `update`. Absent on `delete`.
        #[serde(default, skip_serializing_if = "Option::is_none")]
        value: Option<serde_json::Value>,
    },

    /// A dead-letter row fired this handler. The original event is
    /// nested verbatim plus the dead-letter metadata the design notes
    /// §4 require.
    DeadLetter {
        dead_letter_id: DeadLetterId,
        original: Box<TriggerEvent>,
        attempts: u32,
        last_error: String,
        #[serde(default, skip_serializing_if = "Option::is_none")]
        trigger_id: Option<TriggerId>,
        #[serde(default, skip_serializing_if = "Option::is_none")]
        script_id: Option<ScriptId>,
        first_attempt_at: DateTime<Utc>,
        last_attempt_at: DateTime<Utc>,
    },
}

impl TriggerEvent {
    /// The `source` discriminant the script sees on `ctx.event.source`.
    #[must_use]
    pub const fn source(&self) -> &'static str {
        match self {
            Self::Kv { .. } => "kv",
            Self::DeadLetter { .. } => "dead_letter",
        }
    }
}

/// Convenience accessor on the dead-letter variant for places that
/// already know they're handling a DL event. Pulled out so the
/// dispatcher and the dashboard don't have to repeat the match.
#[derive(Debug, Clone)]
pub struct DeadLetterEventDetail {
    pub dead_letter_id: DeadLetterId,
    pub original: TriggerEvent,
    pub attempts: u32,
    pub last_error: String,
    pub trigger_id: Option<TriggerId>,
    pub script_id: Option<ScriptId>,
    pub first_attempt_at: DateTime<Utc>,
    pub last_attempt_at: DateTime<Utc>,
}