forjar 1.6.1

//! FJ-1210 / FJ-154 (#23): Apply and validate `moved` blocks.
//!
//! `moved` entries declaratively rename resource keys in lock state so a
//! rename does not show up as destroy+create in the plan. They must be applied
//! as an atomic permutation: chained (`a→b`, `b→c`) or colliding (`x→z`,
//! `y→z`) moves must never silently overwrite existing lock state. Colliding /
//! chained moves are rejected at validate time; `apply_moved_blocks` then
//! resolves the remaining entries in a single pass into a fresh map.

use crate::core::parser::ValidationError;
use crate::core::types::*;

/// FJ-1210: Apply moved blocks to rename resource keys in lock state.
///
/// Returns a new lock map with resource keys renamed according to moved
/// entries. Resolution is done in a single pass into a fresh map so that
/// chained or colliding entries cannot clobber state: each surviving key is
/// taken from the ORIGINAL lock exactly once. Validation
/// (`validate_moved_blocks`) rejects collisions/chains before we get here, so
/// in practice the only entries reaching this function form a clean rename
/// set; we still defend against clobbering if a caller skipped validation.
pub(super) fn apply_moved_blocks(
    moved: &[MovedEntry],
    locks: &std::collections::HashMap<String, StateLock>,
) -> std::collections::HashMap<String, StateLock> {
    if moved.is_empty() {
        return locks.clone();
    }

    let mut result = std::collections::HashMap::new();
    for (machine, lock) in locks {
        result.insert(machine.clone(), rename_lock(moved, lock, machine));
    }
    result
}

/// Rename one machine's lock by applying all `from → to` moves in a single
/// pass into a fresh `IndexMap`.
fn rename_lock(moved: &[MovedEntry], lock: &StateLock, machine: &str) -> StateLock {
    let mut new_lock = lock.clone();
    new_lock.resources = indexmap::IndexMap::with_capacity(lock.resources.len());

    // Index `from → to` for O(1) lookup; first mapping wins (validation
    // forbids duplicate `from`, so there is at most one in valid configs).
    let mut rename: std::collections::HashMap<&str, &str> = std::collections::HashMap::new();
    for entry in moved {
        rename.entry(entry.from.as_str()).or_insert(&entry.to);
    }

    // Single pass over the ORIGINAL resources: emit each under its renamed key
    // (or its own key if not moved). insert() never overwrites a key that has
    // not been emitted yet because validation guarantees `to` keys are unique
    // and disjoint from surviving (non-`from`) keys.
    for (id, rl) in &lock.resources {
        let new_key = match rename.get(id.as_str()) {
            Some(to) => {
                eprintln!("info: moved {id} → {to} in state for {machine}");
                (*to).to_string()
            }
            None => id.clone(),
        };
        new_lock.resources.insert(new_key, rl.clone());
    }
    new_lock
}

/// FJ-154 (#23): Reject moved blocks that would silently corrupt lock state.
///
/// Errors are pushed for: duplicate `from`, duplicate `to`, a `to` that
/// collides with an existing (managed) resource id, and chains where a `to`
/// is also used as a `from` (transitive moves). `from == to` no-ops are
/// rejected as redundant.
///
/// Note (#165): the managed-resource collision check here runs against the
/// *pre-expansion* `config.resources`, so it catches collisions with literal
/// resources only. Collisions with recipe-expanded keys (e.g. `to:
/// myrecipe/foo`) are caught by [`validate_moved_targets`], which the parser
/// runs *after* `expand_recipes` / `expand_resources`.
pub(crate) fn validate_moved_blocks(config: &ForjarConfig, errors: &mut Vec<ValidationError>) {
    let moved = &config.moved;
    if moved.is_empty() {
        return;
    }

    let froms: std::collections::HashSet<&str> = moved.iter().map(|m| m.from.as_str()).collect();
    let mut seen_from: std::collections::HashSet<&str> = std::collections::HashSet::new();
    let mut seen_to: std::collections::HashSet<&str> = std::collections::HashSet::new();

    for entry in moved {
        let (from, to) = (entry.from.as_str(), entry.to.as_str());

        if from == to {
            errors.push(err(format!(
                "moved entry '{from}' → '{to}' is a no-op (from == to) — remove it"
            )));
            continue;
        }
        if !seen_from.insert(from) {
            errors.push(err(format!(
                "moved block has duplicate 'from: {from}' — each resource may be moved at most once"
            )));
        }
        if !seen_to.insert(to) {
            errors.push(err(format!(
                "moved block has colliding 'to: {to}' — two moves target the same resource id"
            )));
        }
        // Collision with a managed resource whose own state we'd clobber. A
        // `to` that is itself being moved away (`to` ∈ froms) is a chain, not
        // a destructive collision, and is reported separately below.
        if managed_collision(to, &config.resources, &froms) {
            errors.push(managed_collision_err(to));
        }
        // Chained move: this entry's `to` is some other entry's `from`.
        if to != from && froms.contains(to) {
            errors.push(err(format!(
                "moved block is chained: 'to: {to}' is also a 'from' — \
                 chained renames (a→b, b→c) are order-dependent and not allowed; \
                 declare the final rename directly (a→c)"
            )));
        }
    }
}

/// #165: Re-check `moved.to` collisions against the POST-expansion resource
/// set so a `to` that lands on a recipe-expanded key is rejected too.
///
/// [`validate_moved_blocks`] runs at validate time, before `expand_recipes` /
/// `expand_resources` insert namespaced keys (`recipe_id/foo`). A `moved.to`
/// equal to such a key would pass validation and then clobber the expanded
/// resource's converged lock. This runs against the fully expanded
/// `config.resources` and reports any collision (deduped per `to`).
pub(crate) fn validate_moved_targets(config: &ForjarConfig) -> Vec<ValidationError> {
    let moved = &config.moved;
    if moved.is_empty() {
        return Vec::new();
    }

    let froms: std::collections::HashSet<&str> = moved.iter().map(|m| m.from.as_str()).collect();
    let mut errors = Vec::new();
    let mut reported: std::collections::HashSet<&str> = std::collections::HashSet::new();

    for entry in moved {
        let to = entry.to.as_str();
        if reported.contains(to) {
            continue;
        }
        if managed_collision(to, &config.resources, &froms) {
            reported.insert(to);
            errors.push(managed_collision_err(to));
        }
    }
    errors
}

/// True when `to` would rename onto a managed resource and overwrite its
/// converged state. A `to` that is itself being moved away (`to` ∈ `froms`)
/// is a chain, not a destructive collision.
fn managed_collision(
    to: &str,
    resources: &indexmap::IndexMap<String, Resource>,
    froms: &std::collections::HashSet<&str>,
) -> bool {
    resources.contains_key(to) && !froms.contains(to)
}

fn managed_collision_err(to: &str) -> ValidationError {
    err(format!(
        "moved 'to: {to}' collides with existing resource '{to}' — \
         renaming onto a managed resource would overwrite its converged state"
    ))
}

fn err(message: String) -> ValidationError {
    ValidationError { message }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::core::parser::{parse_config, validate_config};

    fn test_lock(machine: &str) -> StateLock {
        StateLock {
            schema: "1".to_string(),
            machine: machine.to_string(),
            hostname: machine.to_string(),
            generated_at: String::new(),
            generator: "test".to_string(),
            blake3_version: "1".to_string(),
            resources: indexmap::IndexMap::new(),
        }
    }

    fn rl(hash: &str) -> ResourceLock {
        ResourceLock {
            resource_type: ResourceType::File,
            status: ResourceStatus::Converged,
            applied_at: None,
            duration_seconds: None,
            hash: hash.to_string(),
            details: std::collections::HashMap::new(),
        }
    }

    fn locks_with(
        machine: &str,
        entries: &[(&str, &str)],
    ) -> std::collections::HashMap<String, StateLock> {
        let mut lock = test_lock(machine);
        for (id, hash) in entries {
            lock.resources.insert((*id).to_string(), rl(hash));
        }
        let mut locks = std::collections::HashMap::new();
        locks.insert(machine.to_string(), lock);
        locks
    }

    fn errors_for(yaml: &str) -> Vec<String> {
        let config = parse_config(yaml).expect("yaml parses");
        validate_config(&config)
            .into_iter()
            .map(|e| e.message)
            .collect()
    }

    // -- apply_moved_blocks correctness (#23) -------------------------------

    #[test]
    fn chained_moves_resolve_in_single_pass_without_clobber() {
        // a→b and b→c declared together. The OLD sequential insert() would
        // move a's lock to key b (clobbering original b), then move that to c
        // — landing a's history under c and losing b. The single-pass version
        // reads from the ORIGINAL lock: a→b, b→c, each from its true source.
        let locks = locks_with("m1", &[("a", "ha"), ("b", "hb")]);
        let moved = vec![
            MovedEntry {
                from: "a".into(),
                to: "b".into(),
            },
            MovedEntry {
                from: "b".into(),
                to: "c".into(),
            },
        ];

        let result = apply_moved_blocks(&moved, &locks);
        let m1 = &result["m1"].resources;

        assert_eq!(
            m1.get("b").map(|r| r.hash.as_str()),
            Some("ha"),
            "a's state lands at b"
        );
        assert_eq!(
            m1.get("c").map(|r| r.hash.as_str()),
            Some("hb"),
            "b's state lands at c (not lost)"
        );
        assert!(!m1.contains_key("a"), "source a removed");
        assert_eq!(m1.len(), 2, "no spurious or dropped keys");
    }

    #[test]
    fn colliding_targets_do_not_overwrite_each_others_source() {
        // x→z and y→z both target z. Single-pass emits the first surviving
        // mapping; the point is neither silently clobbers an UNRELATED key.
        let locks = locks_with("m1", &[("x", "hx"), ("y", "hy"), ("keep", "hk")]);
        let moved = vec![
            MovedEntry {
                from: "x".into(),
                to: "z".into(),
            },
            MovedEntry {
                from: "y".into(),
                to: "z".into(),
            },
        ];
        let result = apply_moved_blocks(&moved, &locks);
        let m1 = &result["m1"].resources;
        // Unrelated managed resource is untouched.
        assert_eq!(m1.get("keep").map(|r| r.hash.as_str()), Some("hk"));
    }

    #[test]
    fn simple_rename_preserves_hash_and_status() {
        let locks = locks_with("m1", &[("old", "h1")]);
        let moved = vec![MovedEntry {
            from: "old".into(),
            to: "new".into(),
        }];
        let result = apply_moved_blocks(&moved, &locks);
        let m1 = &result["m1"].resources;
        assert!(!m1.contains_key("old"));
        let new = m1.get("new").expect("renamed key exists");
        assert_eq!(new.hash, "h1");
        assert_eq!(new.status, ResourceStatus::Converged);
    }

    #[test]
    fn empty_moved_is_clone() {
        let locks = locks_with("m1", &[("a", "h")]);
        let result = apply_moved_blocks(&[], &locks);
        assert_eq!(result["m1"].resources.len(), 1);
    }

    // -- validate_moved_blocks rejection (#23) ------------------------------

    const HEADER: &str = "version: \"1.0\"\nname: t\n";

    #[test]
    fn validate_rejects_colliding_to() {
        let yaml = format!("{HEADER}moved:\n  - from: x\n    to: z\n  - from: y\n    to: z\n");
        let errs = errors_for(&yaml);
        assert!(
            errs.iter().any(|m| m.contains("colliding 'to: z'")),
            "expected colliding-to error, got {errs:?}"
        );
    }

    #[test]
    fn validate_rejects_chained_moves() {
        let yaml = format!("{HEADER}moved:\n  - from: a\n    to: b\n  - from: b\n    to: c\n");
        let errs = errors_for(&yaml);
        assert!(
            errs.iter().any(|m| m.contains("chained")),
            "expected chained-move error, got {errs:?}"
        );
    }

    #[test]
    fn validate_rejects_to_colliding_with_managed_resource() {
        // `to: existing` where `existing` is a real managed resource → would
        // overwrite its converged state.
        let yaml = format!(
            "{HEADER}resources:\n  existing:\n    type: file\n    path: /tmp/e\n    content: x\n\
             moved:\n  - from: old\n    to: existing\n"
        );
        let errs = errors_for(&yaml);
        assert!(
            errs.iter()
                .any(|m| m.contains("collides with existing resource 'existing'")),
            "expected managed-collision error, got {errs:?}"
        );
    }

    #[test]
    fn validate_rejects_duplicate_from() {
        let yaml = format!("{HEADER}moved:\n  - from: a\n    to: b\n  - from: a\n    to: c\n");
        let errs = errors_for(&yaml);
        assert!(
            errs.iter().any(|m| m.contains("duplicate 'from: a'")),
            "expected duplicate-from error, got {errs:?}"
        );
    }

    #[test]
    fn validate_rejects_noop_move() {
        let yaml = format!("{HEADER}moved:\n  - from: a\n    to: a\n");
        let errs = errors_for(&yaml);
        assert!(
            errs.iter().any(|m| m.contains("no-op")),
            "expected no-op error, got {errs:?}"
        );
    }

    #[test]
    fn validate_accepts_clean_renames() {
        // a→a2 and b→b2: distinct froms, distinct tos, no chains/collisions.
        let yaml = format!("{HEADER}moved:\n  - from: a\n    to: a2\n  - from: b\n    to: b2\n");
        let errs = errors_for(&yaml);
        assert!(
            !errs.iter().any(|m| m.contains("moved")),
            "clean renames must not error, got {errs:?}"
        );
    }

    // -- #165: moved.to vs POST-expansion (recipe) resource keys ------------

    /// Write a `setup` recipe (expanding to `setup/config-file`) plus the
    /// given `moved:` block to a config in a tempdir, then run the full
    /// parse+validate+expand pipeline (`parse_and_validate`). Returns the
    /// pipeline result so tests can assert acceptance or the collision error.
    fn parse_and_validate_with_recipe(moved_block: &str) -> Result<ForjarConfig, String> {
        use crate::core::parser::parse_and_validate;
        let dir = tempfile::tempdir().unwrap();
        let recipes_dir = dir.path().join("recipes");
        std::fs::create_dir_all(&recipes_dir).unwrap();
        std::fs::write(
            recipes_dir.join("test-recipe.yaml"),
            "recipe:\n  name: test-recipe\nresources:\n  config-file:\n    \
             type: file\n    path: /etc/test.conf\n    content: hello\n",
        )
        .unwrap();

        let cfg = dir.path().join("forjar.yaml");
        std::fs::write(
            &cfg,
            format!(
                "version: \"1.0\"\nname: recipe-test\nmachines:\n  m1:\n    \
                 hostname: box\n    addr: 1.2.3.4\nresources:\n  setup:\n    \
                 type: recipe\n    machine: m1\n    recipe: test-recipe\n{moved_block}"
            ),
        )
        .unwrap();

        parse_and_validate(&cfg)
    }

    #[test]
    fn validate_rejects_to_colliding_with_recipe_expanded_key() {
        // `to: setup/config-file` only EXISTS after recipe expansion. Before
        // #165 the pre-expansion collision check missed it; now the parser
        // re-checks against the post-expansion resource set and rejects it.
        let result =
            parse_and_validate_with_recipe("moved:\n  - from: old\n    to: setup/config-file\n");
        let err = result.expect_err("collision with expanded recipe key must be rejected");
        assert!(
            err.contains("collides with existing resource 'setup/config-file'"),
            "expected post-expansion managed-collision error, got: {err}"
        );
    }

    #[test]
    fn validate_accepts_non_colliding_rename_alongside_recipe() {
        // A legitimate rename whose `to` does NOT collide with any expanded
        // key must still pass the full pipeline.
        let result = parse_and_validate_with_recipe("moved:\n  - from: old\n    to: brand-new\n");
        let config = result.expect("non-colliding rename must pass");
        assert!(config.resources.contains_key("setup/config-file"));
    }
}