//! JoinIR routing logic for loop lowering

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

impl MirBuilder {
    /// Phase 49: Try JoinIR Frontend for mainline integration
    ///
    /// Returns `Ok(Some(value))` if the loop is successfully lowered via JoinIR,
    /// `Ok(None)` if no JoinIR pattern matched (unsupported loop structure).
    /// Phase 187-2: Legacy LoopBuilder removed - all loops must use JoinIR.
    ///
    /// # Phase 49-4: Multi-target support
    ///
    /// Targets are enabled via separate dev flags:
    /// - `HAKO_JOINIR_PRINT_TOKENS_MAIN=1`: JsonTokenizer.print_tokens/0
    /// - `HAKO_JOINIR_ARRAY_FILTER_MAIN=1`: ArrayExtBox.filter/2
    ///
    /// Note: Arity in function names does NOT include implicit `me` receiver.
    /// - Instance method `print_tokens()` → `/0` (no explicit params)
    /// - Static method `filter(arr, pred)` → `/2` (two params)
    pub(in crate::mir::builder) fn try_cf_loop_joinir(
        &mut self,
        condition: &ASTNode,
        body: &[ASTNode],
    ) -> Result<Option<ValueId>, String> {
        // Get current function name
        let func_name = self
            .current_function
            .as_ref()
            .map(|f| f.signature.name.clone())
            .unwrap_or_default();

        // Phase 195: Use unified trace
        trace::trace().routing("router", &func_name, "try_cf_loop_joinir called");

        // Phase 170-4: Structure-based routing option
        // When NYASH_JOINIR_STRUCTURE_ONLY=1, skip function name whitelist
        // and route purely based on loop structure analysis
        let structure_only = std::env::var("NYASH_JOINIR_STRUCTURE_ONLY")
            .ok()
            .as_deref()
            == Some("1");

        if structure_only {
            trace::trace().routing("router", &func_name, "Structure-only mode enabled, skipping whitelist");
        } else {
            // Phase 49-4 + Phase 80: Multi-target routing (legacy whitelist)
            // - Core ON なら代表2本（print_tokens / ArrayExt.filter）は JoinIR を優先し、失敗したら LoopBuilder へフォールバック
            // - Core OFF では従来通り dev フラグで opt-in
            // Note: Arity does NOT include implicit `me` receiver
            // Phase 188: Add "main" routing for loop pattern expansion
            // Phase 170: Add JsonParserBox methods for selfhost validation
            let core_on = crate::config::env::joinir_core_enabled();
            let is_target = match func_name.as_str() {
                "main" => true,  // Phase 188-Impl-1: Enable JoinIR for main function (Pattern 1)
                "JoinIrMin.main/0" => true,  // Phase 188-Impl-2: Enable JoinIR for JoinIrMin.main/0 (Pattern 2)
                "JsonTokenizer.print_tokens/0" => {
                    if core_on {
                        true
                    } else {
                        std::env::var("HAKO_JOINIR_PRINT_TOKENS_MAIN")
                            .ok()
                            .as_deref()
                            == Some("1")
                    }
                }
                "ArrayExtBox.filter/2" => {
                    if core_on {
                        true
                    } else {
                        std::env::var("HAKO_JOINIR_ARRAY_FILTER_MAIN")
                            .ok()
                            .as_deref()
                            == Some("1")
                    }
                }
                // Phase 170-A-1: Enable JsonParserBox methods for JoinIR routing
                "JsonParserBox._trim/1" => true,
                "JsonParserBox._skip_whitespace/2" => true,
                "JsonParserBox._match_literal/2" => true,
                "JsonParserBox._parse_string/2" => true,
                "JsonParserBox._parse_array/2" => true,
                "JsonParserBox._parse_object/2" => true,
                // Phase 170-A-1: Test methods (simplified versions)
                "TrimTest.trim/1" => true,
                "Main.trim/1" => true,  // Phase 171-fix: Main box variant
                "Main.trim_string_simple/1" => true,  // Phase 33-13: Simple trim variant
                "TrimTest.main/0" => true,  // Phase 170: TrimTest.main for loop pattern test
                // Phase 173: JsonParser P5 expansion test
                "JsonParserTest._skip_whitespace/3" => true,
                "JsonParserTest.main/0" => true,
                // Phase 174: JsonParser complex loop P5B extension test
                "JsonParserStringTest.parse_string_min/0" => true,
                "JsonParserStringTest.main/0" => true,
                // Phase 175: P5 multi-carrier support (2 carriers: pos + result)
                "JsonParserStringTest2.parse_string_min2/0" => true,
                "JsonParserStringTest2.main/0" => true,
                _ => false,
            };

            if !is_target {
                return Ok(None);
            }
        }

        // Debug log when routing through JoinIR Frontend
        // Phase 195: Check trace flags directly from JoinLoopTrace
        let debug = trace::trace().is_loopform_enabled() || trace::trace().is_mainline_enabled();
        trace::trace().routing("router", &func_name, "Routing through JoinIR Frontend mainline");

        // Phase 49-3: Implement JoinIR Frontend integration
        self.cf_loop_joinir_impl(condition, body, &func_name, debug)
    }

    /// Phase 49-3: JoinIR Frontend integration implementation
    ///
    /// Routes loop compilation through either:
    /// 1. Pattern-based router (Phase 194+) - preferred for new patterns
    /// 2. Legacy binding path (Phase 49-3) - for whitelisted functions only
    pub(in crate::mir::builder) fn cf_loop_joinir_impl(
        &mut self,
        condition: &ASTNode,
        body: &[ASTNode],
        func_name: &str,
        debug: bool,
    ) -> Result<Option<ValueId>, String> {
        // Phase 194: Use table-driven router instead of if/else chain
        use super::patterns::{route_loop_pattern, LoopPatternContext};

        let ctx = LoopPatternContext::new(condition, body, &func_name, debug);
        if let Some(result) = route_loop_pattern(self, &ctx)? {
            trace::trace().routing("router", func_name, "Pattern router succeeded");
            return Ok(Some(result));
        }

        // Phase 187-2: Pattern router failed, try legacy whitelist
        trace::trace().routing("router", func_name, "Pattern router found no match, trying legacy whitelist");

        // Delegate to legacy binding path (routing_legacy_binding.rs)
        self.cf_loop_joinir_legacy_binding(condition, body, func_name, debug)
    }
}