//! Write operations for the pipeline — content, stage transitions, and deletions.
//!
//! Each function updates three layers atomically in order: the in-memory
//! content store, the CRDT (source of truth for metadata), and the SQLite
//! shadow table (via the background channel).
use super::content_store::{
    ContentKey, all_content_ids, delete_content, ensure_content_store, read_content, write_content,
};
use super::shadow_write::{PIPELINE_DB, PipelineWriteMsg};

/// Typed metadata for a pipeline item write.
///
/// Story 929: callers pass metadata explicitly — no YAML parsing.  Every
/// field is `Option`-typed; `None` means "leave unchanged" on update,
/// "use the default" on insert.
#[derive(Default, Clone, Debug)]
pub struct ItemMeta {
    pub name: Option<String>,
    pub agent: Option<String>,
    pub retry_count: Option<i64>,
    pub depends_on: Option<Vec<u32>>,
}

impl ItemMeta {
    /// Convenience constructor for the common "just set a name" case.
    #[cfg(test)]
    pub fn named(name: impl Into<String>) -> Self {
        Self {
            name: Some(name.into()),
            ..Self::default()
        }
    }
}

/// Normalise a stage string at the db boundary.
///
/// Accepts the clean post-934 vocabulary (passthrough) and the pre-934
/// directory-style strings (`"2_current"`, `"4_merge"`, etc.) by mapping
/// them to the clean form before handing off to `Stage::from_dir` (which
/// itself only accepts clean form after stage 6).  This keeps the public
/// db API tolerant for callers that still pass legacy strings while the
/// internal type stays strict.
fn normalise_stage_str(stage: &str) -> &str {
    match stage {
        "0_upcoming" => "upcoming",
        "1_backlog" => "backlog",
        "2_current" => "coding",
        "2_blocked" => "blocked",
        "3_qa" => "qa",
        "4_merge" => "merge",
        "4_merge_failure" => "merge_failure",
        "4_merge_failure_final" => "merge_failure_final",
        "5_done" => "done",
        "6_archived" => "archived",
        "7_frozen" => "frozen",
        "7_review_hold" => "review_hold",
        other => other,
    }
}

/// Write a pipeline item from in-memory content (no filesystem access).
///
/// This is the primary write path for the DB-backed pipeline.  It updates
/// the CRDT, the in-memory content store, and the SQLite shadow table.
///
/// The metadata in `meta` is authoritative: this function does NOT parse
/// `content` to extract front-matter fields.  Callers must pass typed
/// metadata explicitly via `ItemMeta`.
pub fn write_item_with_content(story_id: &str, stage: &str, content: &str, meta: ItemMeta) {
    let depends_on_json = meta
        .depends_on
        .as_ref()
        .and_then(|d| serde_json::to_string(d).ok());

    // Update in-memory content store.
    ensure_content_store();
    write_content(ContentKey::Story(story_id), content);

    // Primary: CRDT ops.
    let stage = normalise_stage_str(stage);
    let Some(typed_stage) = crate::pipeline_state::Stage::from_dir(stage) else {
        crate::slog!(
            "[db] write_item_with_content: unknown stage '{stage}' for {story_id}; skipping CRDT write"
        );
        return;
    };
    let merged_at_ts = matches!(typed_stage, crate::pipeline_state::Stage::Done { .. })
        .then(|| chrono::Utc::now().timestamp() as f64);
    crate::crdt_state::write_item(
        story_id,
        &typed_stage,
        meta.name.as_deref(),
        meta.agent.as_deref(),
        meta.retry_count,
        depends_on_json.as_deref(),
        None,
        None,
        merged_at_ts,
    );

    // Shadow: pipeline_items table (only when DB is initialised).
    if let Some(db) = PIPELINE_DB.get() {
        let msg = PipelineWriteMsg {
            story_id: story_id.to_string(),
            stage: stage.to_string(),
            name: meta.name,
            agent: meta.agent,
            retry_count: meta.retry_count,
            depends_on: depends_on_json,
            content: Some(content.to_string()),
        };
        let _ = db.tx.send(msg);
    }
}

/// Update only the stage of an existing item (used by move operations).
///
/// Reads current content from the in-memory store, updates the CRDT stage,
/// and persists the change.  Optionally modifies the content (e.g. to clear
/// front-matter fields).
pub fn move_item_stage(
    story_id: &str,
    new_stage: &str,
    content_transform: Option<&dyn Fn(&str) -> String>,
) {
    let current_content = read_content(ContentKey::Story(story_id));

    let content = match (&current_content, content_transform) {
        (Some(c), Some(transform)) => {
            let new_content = transform(c);
            write_content(ContentKey::Story(story_id), &new_content);
            Some(new_content)
        }
        (Some(c), None) => Some(c.clone()),
        _ => None,
    };

    // Story 929: metadata (name/agent/depends_on) is owned by the CRDT typed
    // registers — no need to re-derive it from the content body's YAML front
    // matter on every stage transition.  Pass `None` for those fields so
    // write_item leaves the existing registers untouched.
    let new_stage = normalise_stage_str(new_stage);
    let Some(typed_stage) = crate::pipeline_state::Stage::from_dir(new_stage) else {
        crate::slog!(
            "[db] move_item_stage: unknown stage '{new_stage}' for {story_id}; skipping CRDT write"
        );
        return;
    };
    let merged_at_ts = matches!(typed_stage, crate::pipeline_state::Stage::Done { .. })
        .then(|| chrono::Utc::now().timestamp() as f64);
    crate::crdt_state::write_item(
        story_id,
        &typed_stage,
        None,
        None,
        None,
        None,
        None,
        None,
        merged_at_ts,
    );
    // Bug 780: stage transitions reset retry_count to 0.  retry_count tracks
    // attempts at THIS stage's work (coding, merging, qa); a fresh attempt at
    // a new stage is conceptually distinct from prior attempts at a different
    // stage.  `blocked` is preserved — that's a human-set signal that survives
    // transitions.
    crate::crdt_state::set_retry_count(story_id, 0);

    // Shadow table — read current metadata from the CRDT so the SQLite
    // mirror stays in sync.  Always reset retry_count to 0 on stage transition.
    if let Some(db) = PIPELINE_DB.get() {
        let view = crate::crdt_state::read_item(story_id);
        let name = view.as_ref().map(|v| v.name().to_string());
        let agent = view.as_ref().and_then(|v| v.agent().map(str::to_string));
        let depends_on = view
            .as_ref()
            .map(|v| v.depends_on())
            .filter(|d| !d.is_empty())
            .and_then(|d| serde_json::to_string(d).ok());
        let msg = PipelineWriteMsg {
            story_id: story_id.to_string(),
            stage: new_stage.to_string(),
            name,
            agent,
            retry_count: Some(0),
            depends_on,
            content,
        };
        let _ = db.tx.send(msg);
    }
}

/// Delete a story from the shadow table (fire-and-forget).
pub fn delete_item(story_id: &str) {
    delete_content(ContentKey::Story(story_id));

    if let Some(db) = PIPELINE_DB.get() {
        // Reuse the channel with a special "deleted" stage marker.
        // The background task will handle it.
        // Actually, we send a delete message by abusing the write — we'll
        // just remove it by setting stage to "deleted".
        let msg = PipelineWriteMsg {
            story_id: story_id.to_string(),
            stage: "deleted".to_string(),
            name: None,
            agent: None,
            retry_count: None,
            depends_on: None,
            content: None,
        };
        let _ = db.tx.send(msg);
    }
}

/// Get the next available item number by scanning both the CRDT state
/// and the in-memory content store for the highest existing number.
pub fn next_item_number() -> u32 {
    let mut max_num: u32 = 0;

    // Scan CRDT items via typed projection.
    for item in crate::pipeline_state::read_all_typed() {
        let num_str: String = item
            .story_id
            .0
            .chars()
            .take_while(|c| c.is_ascii_digit())
            .collect();
        if let Ok(n) = num_str.parse::<u32>()
            && n > max_num
        {
            max_num = n;
        }
    }

    // Also scan the content store (might have items not yet in CRDT).
    for id in all_content_ids() {
        let num_str: String = id.chars().take_while(|c| c.is_ascii_digit()).collect();
        if let Ok(n) = num_str.parse::<u32>()
            && n > max_num
        {
            max_num = n;
        }
    }

    max_num + 1
}