//! Pattern Router - Plan/Composer routing for loop patterns
//!
//! Phase 29ap P12: Legacy loop table removed (plan/composer SSOT only)
//!
//! # Architecture
//!
//! - single_planner derives a DomainPlan + facts outcome (SSOT)
//! - composer adopts CorePlan (strict/dev shadow or release adopt)
//! - PlanLowerer emits MIR from CorePlan (emit_frag SSOT)
//!
//! # Adding New Patterns
//!
//! 1. Add Facts/Planner extraction in plan layer
//! 2. Normalize/verify in plan normalizer/verifier
//! 3. Compose CorePlan in composer (shadow/release adopt as needed)
//! 4. Keep router unchanged (it only delegates to plan/composer)

use crate::ast::ASTNode;
use crate::mir::builder::MirBuilder;
use crate::mir::ValueId;

use crate::mir::loop_pattern_detection::{LoopFeatures, LoopPatternKind};

// Phase 273 P1: Import Plan components (DomainPlan → Normalizer → Verifier → Lowerer)
use crate::mir::builder::control_flow::plan::lowerer::PlanLowerer;
use crate::mir::builder::control_flow::plan::normalizer::PlanNormalizer;
use crate::mir::builder::control_flow::plan::verifier::PlanVerifier;
use crate::mir::builder::control_flow::plan::composer;
use crate::mir::builder::control_flow::plan::single_planner;

/// AST Feature Extractor (declared in mod.rs as pub module, import from parent)
use super::ast_feature_extractor as ast_features;

/// Phase 92 P0-2: Import LoopSkeleton for Option A
use crate::mir::loop_canonicalizer::LoopSkeleton;

/// Context passed to pattern detect/lower functions
pub(crate) struct LoopPatternContext<'a> {
    /// Loop condition AST node
    pub condition: &'a ASTNode,

    /// Loop body statements
    pub body: &'a [ASTNode],

    /// Current function name (for routing)
    pub func_name: &'a str,

    /// Debug logging enabled
    pub debug: bool,

    /// In static box context? (affects Pattern8 routing)
    pub in_static_box: bool,

    /// Has continue statement(s) in body? (Phase 194+)
    #[allow(dead_code)]
    pub has_continue: bool,

    /// Has break statement(s) in body? (Phase 194+)
    #[allow(dead_code)]
    pub has_break: bool,

    /// Phase 192: Loop features extracted from AST
    #[allow(dead_code)]
    pub features: LoopFeatures,

    /// Phase 192: Pattern classification based on features
    pub pattern_kind: LoopPatternKind,

    /// Phase 200-C: Optional function body AST for capture analysis
    /// None if not available, Some(&[ASTNode]) if function body is accessible
    pub fn_body: Option<&'a [ASTNode]>,

    /// Phase 92 P0-2: Optional LoopSkeleton from canonicalizer
    /// This provides ConditionalStep information for Pattern2 lowering.
    /// None if canonicalizer hasn't run yet (backward compatibility).
    /// SSOT Principle: Avoid re-detecting ConditionalStep in lowering phase.
    #[allow(dead_code)]
    pub skeleton: Option<&'a LoopSkeleton>,

    /// Phase 188.3: Cached StepTree max_loop_depth for Pattern6
    /// None if not computed, Some(depth) if Pattern6 candidate
    /// Avoids re-building StepTree in lowering phase
    pub step_tree_max_loop_depth: Option<u32>,
}

impl<'a> LoopPatternContext<'a> {
    /// Create new context from routing parameters
    ///
    /// Automatically detects continue/break statements in body
    /// Extracts features and classifies pattern from AST
    /// Detects infinite loop condition
    /// Uses choose_pattern_kind() SSOT entry point
    pub(crate) fn new(
        condition: &'a ASTNode,
        body: &'a [ASTNode],
        func_name: &'a str,
        debug: bool,
        in_static_box: bool,
    ) -> Self {
        // Use AST Feature Extractor for break/continue detection
        let has_continue = ast_features::detect_continue_in_body(body);
        let has_break = ast_features::detect_break_in_body(body);

        // Extract features (includes infinite loop detection)
        let features = ast_features::extract_features(condition, body, has_continue, has_break);

        // Phase 137-6-S1: Use SSOT pattern selection entry point
        use crate::mir::builder::control_flow::joinir::routing::choose_pattern_kind;
        let pattern_kind = choose_pattern_kind(condition, body);

        Self {
            condition,
            body,
            func_name,
            debug,
            in_static_box,
            has_continue,
            has_break,
            features,
            pattern_kind,
            fn_body: None, // Phase 200-C: Default to None
            skeleton: None, // Phase 92 P0-2: Default to None
            step_tree_max_loop_depth: None, // Phase 188.3: Default to None
        }
    }

    /// Phase 200-C: Create context with fn_body for capture analysis
    pub(crate) fn with_fn_body(
        condition: &'a ASTNode,
        body: &'a [ASTNode],
        func_name: &'a str,
        debug: bool,
        in_static_box: bool,
        fn_body: &'a [ASTNode],
    ) -> Self {
        let mut ctx = Self::new(condition, body, func_name, debug, in_static_box);
        ctx.fn_body = Some(fn_body);
        ctx
    }

    /// Phase 92 P0-2: Set skeleton (for canonicalizer integration)
    #[allow(dead_code)]
    pub(crate) fn with_skeleton(mut self, skeleton: &'a LoopSkeleton) -> Self {
        self.skeleton = Some(skeleton);
        self
    }
}

/// Phase 286 P2.2: Common helper for Plan line lowering
///
/// Extracts the common 3-line pattern used by Plan-based routing:
/// 1. Normalize DomainPlan → CorePlan
/// 2. Verify CorePlan invariants (fail-fast)
/// 3. Lower CorePlan → MIR
///
/// This eliminates repetition across 4 pattern routing blocks.
fn lower_via_plan(
    builder: &mut MirBuilder,
    domain_plan: crate::mir::builder::control_flow::plan::DomainPlan,
    ctx: &LoopPatternContext,
) -> Result<Option<ValueId>, String> {
    let core_plan = PlanNormalizer::normalize(builder, domain_plan, ctx)?;
    PlanVerifier::verify(&core_plan)?;
    PlanLowerer::lower(builder, core_plan, ctx)
}

// Phase 29ai P5: Plan extractor routing moved to `plan::single_planner`.

/// Route loop patterns via plan/composer SSOT.
///
/// Returns Ok(Some(value_id)) if a plan matched and lowered successfully.
/// Returns Ok(None) if no plan matched.
/// Returns Err if a plan matched but lowering failed.
///
/// # Router Architecture (Plan/Composer SSOT)
///
/// The plan line (Extractor → Normalizer → Verifier → Lowerer) is the
/// operational SSOT for loop routing (Phase 273+).
///
/// Plan-based architecture (Phase 273 P1-P3):
/// - extract_*_plan() → DomainPlan (pure extraction, no builder)
/// - PlanNormalizer::normalize() → CorePlan (pattern knowledge expansion, SSOT)
/// - PlanVerifier::verify() → fail-fast validation
/// - PlanLowerer::lower() → MIR emission (pattern-agnostic, emit_frag SSOT)
///
/// SSOT Entry Points:
/// - Pattern6: src/mir/builder/control_flow/plan/normalizer.rs (ScanWithInit normalization)
/// - Pattern7: src/mir/builder/control_flow/plan/normalizer.rs (SplitScan normalization)
pub(crate) fn route_loop_pattern(
    builder: &mut MirBuilder,
    ctx: &LoopPatternContext,
) -> Result<Option<ValueId>, String> {
    use super::super::trace;

    // Phase 29ai P5: Single entrypoint for plan extraction (router has no rule table).
    let (domain_plan, outcome) = single_planner::try_build_domain_plan_with_outcome(ctx)?;
    let strict_or_dev = crate::config::env::joinir_dev::strict_enabled()
        || crate::config::env::joinir_dev_enabled();

    if strict_or_dev {
        if let Some(adopt) = composer::try_shadow_adopt_nested_minimal(builder, ctx, &outcome)? {
            let composer::ShadowAdoptOutcome { core_plan, tag } = adopt;
            PlanVerifier::verify(&core_plan)?;
            eprintln!("{}", tag);
            return PlanLowerer::lower(builder, core_plan, ctx);
        }

        if let Some(err) = composer::strict_nested_loop_guard(&outcome, ctx) {
            eprintln!("{}", err);
            return Err(err);
        }
    }

    if !strict_or_dev {
        if let Some(core_plan) =
            composer::try_release_adopt_nested_minimal(builder, ctx, &outcome)?
        {
            PlanVerifier::verify(&core_plan)?;
            return PlanLowerer::lower(builder, core_plan, ctx);
        }
    }

    if let Some(domain_plan) = domain_plan {

        if let Some(adopt) = composer::try_shadow_adopt_core_plan(
            builder,
            ctx,
            strict_or_dev,
            &domain_plan,
            &outcome,
        )? {
            let composer::ShadowAdoptOutcome { core_plan, tag } = adopt;
            PlanVerifier::verify(&core_plan)?;
            eprintln!("{}", tag);
            return PlanLowerer::lower(builder, core_plan, ctx);
        }

        if !strict_or_dev {
            if let Some(core_plan) =
                composer::try_release_adopt_core_plan(builder, ctx, &domain_plan, &outcome)?
            {
                PlanVerifier::verify(&core_plan)?;
                return PlanLowerer::lower(builder, core_plan, ctx);
            }
        }

        return lower_via_plan(builder, domain_plan, ctx);
    }

    // No pattern matched - return None (caller will handle error)
    if ctx.debug {
        trace::trace().debug(
            "route",
            &format!(
                "route=none (no pattern matched) func='{}' pattern_kind={:?} (exhausted: plan+joinir)",
                ctx.func_name, ctx.pattern_kind
            ),
        );
    }
    Ok(None)
}