100 lines
3.3 KiB
Rust
100 lines
3.3 KiB
Rust
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//! Single entry point for pipeline state transitions.
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//!
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//! [`apply_transition`] is the **only** function that should mutate a story's
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//! pipeline stage. It reads the current typed stage from the CRDT, validates
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//! the transition via the pure [`super::transition()`] function, writes the new
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//! stage back to the CRDT, and returns a [`TransitionFired`] event for
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//! downstream subscribers.
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use super::{
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PipelineEvent, StoryId, TransitionFired, event_label, read_typed, stage_label, transition,
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};
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use chrono::Utc;
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/// Error type for [`apply_transition`].
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#[derive(Debug)]
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pub enum ApplyError {
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/// The story was not found in the CRDT.
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NotFound(String),
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/// The CRDT projection failed.
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Projection(super::ProjectionError),
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/// The transition was invalid for the current stage.
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InvalidTransition(super::TransitionError),
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}
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impl std::fmt::Display for ApplyError {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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match self {
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Self::NotFound(id) => write!(f, "story '{id}' not found in CRDT"),
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Self::Projection(e) => write!(f, "projection error: {e}"),
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Self::InvalidTransition(e) => write!(f, "{e}"),
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}
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}
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}
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impl std::error::Error for ApplyError {}
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impl From<super::ProjectionError> for ApplyError {
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fn from(e: super::ProjectionError) -> Self {
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Self::Projection(e)
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}
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}
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impl From<super::TransitionError> for ApplyError {
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fn from(e: super::TransitionError) -> Self {
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Self::InvalidTransition(e)
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}
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}
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/// Apply a pipeline event to a story, validating the transition and writing
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/// the new stage to the CRDT.
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///
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/// This is the single canonical entry point for all pipeline stage mutations.
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/// Returns a [`TransitionFired`] describing what happened, suitable for
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/// broadcasting to event-bus subscribers and CRDT log consumers.
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///
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/// An optional `content_transform` allows callers to modify the stored content
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/// (e.g. clearing front-matter fields) atomically with the stage change.
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pub fn apply_transition(
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story_id: &str,
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event: PipelineEvent,
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content_transform: Option<&dyn Fn(&str) -> String>,
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) -> Result<TransitionFired, ApplyError> {
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let item = read_typed(story_id)?.ok_or_else(|| ApplyError::NotFound(story_id.to_string()))?;
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let before = item.stage.clone();
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let after = transition(before.clone(), event.clone())?;
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let new_dir = after.dir_name();
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// Write the new stage to the CRDT (with optional content transform).
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crate::db::move_item_stage(story_id, new_dir, content_transform);
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let fired = TransitionFired {
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story_id: StoryId(story_id.to_string()),
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before,
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after,
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event,
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at: Utc::now(),
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};
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crate::slog!(
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"[pipeline/transition] #{}: {} + {} → {}",
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story_id,
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stage_label(&fired.before),
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event_label(&fired.event),
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stage_label(&fired.after),
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);
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Ok(fired)
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}
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/// Convenience: apply a transition, returning an `Err(String)` on failure
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/// (matches the existing lifecycle function signatures).
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pub fn apply_transition_str(
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story_id: &str,
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event: PipelineEvent,
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content_transform: Option<&dyn Fn(&str) -> String>,
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) -> Result<TransitionFired, String> {
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apply_transition(story_id, event, content_transform).map_err(|e| e.to_string())
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}
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