heddle-cli 0.2.3

// SPDX-License-Identifier: Apache-2.0
//! Collapse command: squash multiple states into one.

use std::time::Instant;

use anyhow::Result;
use objects::object::State;
use refs::Head;
use repo::Repository;
use serde::Serialize;

use crate::{
    cli::{Cli, commands::snapshot::resolve_attribution, should_output_json},
    config::UserConfig,
};

#[derive(Serialize)]
struct CollapseOutput {
    change_id: String,
    content_hash: String,
    collapsed_count: usize,
    intent: Option<String>,
    message: String,
}

/// Collapse (squash) multiple states into a single state.
///
/// The resulting state has:
/// - The tree from the last state in the sequence
/// - The parents of the first state in the sequence
/// - A new intent (from --into) summarizing the collapsed work
/// - A new confidence (optional)
///
/// This is useful for cleaning up exploratory work before sharing.
pub fn cmd_collapse(
    cli: &Cli,
    states: Vec<String>,
    into: String,
    confidence: Option<f32>,
) -> Result<()> {
    let repo = Repository::open(cli.repo.as_ref().unwrap_or(&std::env::current_dir()?))?;
    let json = should_output_json(cli, Some(repo.config()));

    if states.is_empty() {
        return Err(anyhow::anyhow!("No states specified to collapse"));
    }

    let started = Instant::now();
    if !json {
        eprintln!("Collapsing {} states: resolving state ids...", states.len());
    }

    // Resolve all state specifiers to actual states
    let mut resolved_states = Vec::new();
    for state_spec in &states {
        let change_id = repo
            .resolve_state(state_spec)?
            .ok_or_else(|| anyhow::anyhow!("State not found: {}", state_spec))?;
        let state = repo
            .store()
            .get_state(&change_id)?
            .ok_or_else(|| anyhow::anyhow!("State not found: {}", state_spec))?;
        resolved_states.push(state);
    }

    // The new state uses:
    // - Tree from the LAST state (most recent content)
    // - Parents from the FIRST state (preserving history connection)
    let first_state = &resolved_states[0];
    let last_state = &resolved_states[resolved_states.len() - 1];
    if !json {
        eprintln!("Using final tree from {}", last_state.change_id.short());
    }

    // Get attribution for the new state
    let user_config = UserConfig::load_default()?;
    let attribution = resolve_attribution(&repo, &user_config)?;

    // Create the collapsed state
    let mut new_state =
        State::new_collapse_of(last_state.tree, first_state.parents.clone(), attribution);
    new_state = new_state.with_intent(into.clone());

    if let Some(provenance) = repo.get_state_provenance_root(last_state)? {
        new_state = new_state.with_provenance(provenance);
    }

    if let Some(conf) = confidence {
        new_state = new_state.with_confidence(conf);
    }

    // Store the new state
    repo.store().put_state(&new_state)?;
    if !json {
        eprintln!("Writing collapsed state {}...", new_state.change_id.short());
    }

    // Update HEAD to point to the new state
    match repo.refs().read_head()? {
        Head::Attached { ref thread } => {
            repo.refs().set_thread(thread, &new_state.change_id)?;
        }
        Head::Detached { .. } => {
            repo.refs().write_head(&Head::Detached {
                state: new_state.change_id,
            })?;
        }
    }

    // Record in oplog
    let source_ids: Vec<_> = resolved_states.iter().map(|s| s.change_id).collect();
    repo.oplog()
        .record_collapse(&source_ids, &new_state.change_id)?;

    let output = CollapseOutput {
        change_id: new_state.change_id.short(),
        content_hash: new_state.compute_hash().short(),
        collapsed_count: resolved_states.len(),
        intent: Some(into),
        message: format!(
            "Collapsed {} states into {}",
            resolved_states.len(),
            new_state.change_id.short()
        ),
    };

    if json {
        println!("{}", serde_json::to_string(&output)?);
    } else {
        println!(
            "{} in {:.1}s",
            output.message,
            started.elapsed().as_secs_f32()
        );
    }

    Ok(())
}