//! 剧情领域事件。
//!
//! 事件只表达 story session 已经发生的领域事实；是否写入 SpacetimeDB event table 或
//! 映射成 HTTP/SSE 输出，由外层 adapter 决定。

use crate::domain::StorySessionSnapshot;
use serde::{Deserialize, Serialize};
use shared_kernel::build_prefixed_seed_id;
#[cfg(feature = "spacetime-types")]
use spacetimedb::SpacetimeType;

/// 剧情事件 ID 的稳定前缀。
pub const STORY_EVENT_ID_PREFIX: &str = "storyevt_";

/// 剧情事件类型，当前覆盖开局和续写两条最小主链。
#[cfg_attr(feature = "spacetime-types", derive(SpacetimeType))]
#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub enum StoryEventKind {
    SessionStarted,
    StoryContinued,
}

impl StoryEventKind {
    pub fn as_str(&self) -> &'static str {
        match self {
            Self::SessionStarted => "session_started",
            Self::StoryContinued => "story_continued",
        }
    }
}

#[cfg_attr(feature = "spacetime-types", derive(SpacetimeType))]
#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub struct StoryEventSnapshot {
    pub event_id: String,
    pub story_session_id: String,
    pub event_kind: StoryEventKind,
    pub narrative_text: String,
    pub choice_function_id: Option<String>,
    pub created_at_micros: i64,
}

pub fn build_story_started_event(snapshot: &StorySessionSnapshot) -> StoryEventSnapshot {
    StoryEventSnapshot {
        event_id: generate_story_event_id(snapshot.created_at_micros),
        story_session_id: snapshot.story_session_id.clone(),
        event_kind: StoryEventKind::SessionStarted,
        narrative_text: snapshot
            .opening_summary
            .clone()
            .unwrap_or_else(|| snapshot.initial_prompt.clone()),
        choice_function_id: None,
        created_at_micros: snapshot.created_at_micros,
    }
}

pub fn generate_story_event_id(seed_micros: i64) -> String {
    build_prefixed_seed_id(STORY_EVENT_ID_PREFIX, seed_micros)
}