//! 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 current function should use JoinIR Frontend,
    /// `Ok(None)` to fall through to the legacy LoopBuilder path.
    ///
    /// # 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
                _ => 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
    ///
    /// # Pipeline
    /// 1. Build Loop AST → JSON v0 format (with "defs" array)
    /// 2. AstToJoinIrLowerer::lower_program_json() → JoinModule
    /// 3. convert_join_module_to_mir_with_meta() → MirModule
    /// 4. Merge MIR blocks into current_function
    ///
    /// # Phase 49-4 Note
    ///
    /// JoinIR Frontend expects a complete function definition with:
    /// - local variable initializations
    /// - loop body
    /// - return statement
    ///
    /// Since cf_loop only has access to the loop condition and body,
    /// we construct a minimal JSON v0 wrapper with function name "simple"
    /// to match the JoinIR Frontend's expected pattern.
    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> {
        use super::super::super::loop_frontend_binding::LoopFrontendBinding;
        use crate::mir::join_ir::frontend::{AstToJoinIrLowerer, JoinFuncMetaMap};
        use crate::mir::join_ir_vm_bridge::convert_join_module_to_mir_with_meta;
        use crate::mir::types::ConstValue;
        use crate::mir::MirInstruction;
        use crate::r#macro::ast_json::ast_to_json;

        // Phase 194: Use table-driven router instead of if/else chain
        // This makes adding new patterns trivial - just add an entry to LOOP_PATTERNS table
        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)? {
            // Phase 195: Use unified trace
            trace::trace().routing("router", func_name, "Pattern router succeeded");
            return Ok(Some(result));
        }

        // Phase 195: Use unified trace
        trace::trace().routing("router", func_name, "Pattern router found no match, continuing to legacy path");

        // Phase 50: Create appropriate binding based on function name
        let binding = match func_name {
            "JsonTokenizer.print_tokens/0" => LoopFrontendBinding::for_print_tokens(),
            "ArrayExtBox.filter/2" => LoopFrontendBinding::for_array_filter(),
            _ => {
                // Phase 195: Use unified trace
                trace::trace().routing("router", func_name, "No binding defined, falling back");
                return Ok(None);
            }
        };

        // Phase 195: Use unified trace
        trace::trace().debug(
            "router",
            &format!(
                "Using binding for '{}': counter={}, acc={:?}, pattern={:?}",
                func_name, binding.counter_var, binding.accumulator_var, binding.pattern
            ),
        );

        // Step 1: Convert condition and body to JSON
        let condition_json = ast_to_json(condition);
        let mut body_json: Vec<serde_json::Value> = body.iter().map(|s| ast_to_json(s)).collect();

        // Phase 50: Rename variables in body (e.g., "out" → "acc" for filter)
        binding.rename_body_variables(&mut body_json);

        // Phase 50: Generate Local declarations from binding
        let (i_local, acc_local, n_local) = binding.generate_local_declarations();

        // Phase 52/56: Build params from external_refs
        // Instance methods need `me`, static methods need their parameters (arr, pred, etc.)
        let mut params: Vec<serde_json::Value> = Vec::new();

        // Phase 52: Add 'me' for instance methods
        if binding.needs_me_receiver() {
            // Phase 195: Use unified trace
            trace::trace().debug("router", "Adding 'me' to params (instance method)");
            params.push(serde_json::json!("me"));
        }

        // Phase 56: Add external_refs as parameters (arr, pred for filter)
        for ext_ref in &binding.external_refs {
            // Skip "me" and "me.*" as they're handled above
            if ext_ref == "me" || ext_ref.starts_with("me.") {
                continue;
            }
            // Phase 195: Use unified trace
            trace::trace().debug("router", &format!("Adding '{}' to params (external_ref)", ext_ref));
            params.push(serde_json::json!(ext_ref));
        }

        // Step 2: Construct JSON v0 format with "defs" array
        // The function is named "simple" to match JoinIR Frontend's pattern matching
        // Phase 50: Include i/acc/n Local declarations to satisfy JoinIR Frontend expectations
        let program_json = serde_json::json!({
            "defs": [
                {
                    "name": "simple",
                    "params": params,
                    "body": {
                        "type": "Block",
                        "body": [
                            // Phase 50: Inject i/acc/n Local declarations
                            i_local,
                            acc_local,
                            n_local,
                            {
                                "type": "Loop",
                                "cond": condition_json,  // JoinIR Frontend expects "cond" not "condition"
                                "body": body_json
                            },
                            // Return the accumulator (or null for side-effect loops)
                            {
                                "type": "Return",
                                "value": { "kind": "Variable", "name": "acc" }
                            }
                        ]
                    }
                }
            ]
        });

        // Phase 195: Use unified trace
        trace::trace().debug(
            "router",
            &format!(
                "Generated JSON v0 for {}: {}",
                func_name,
                serde_json::to_string_pretty(&program_json).unwrap_or_default()
            ),
        );

        // Step 3: Lower to JoinIR
        // Phase 49-4: Use catch_unwind for graceful fallback on unsupported patterns
        // The JoinIR Frontend may panic if the loop doesn't match expected patterns
        // (e.g., missing variable initializations like "i must be initialized")
        let join_module = {
            let json_clone = program_json.clone();
            let result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
                let mut lowerer = AstToJoinIrLowerer::new();
                lowerer.lower_program_json(&json_clone)
            }));

            match result {
                Ok(module) => module,
                Err(e) => {
                    // Extract panic message for debugging
                    let panic_msg = if let Some(s) = e.downcast_ref::<&str>() {
                        s.to_string()
                    } else if let Some(s) = e.downcast_ref::<String>() {
                        s.clone()
                    } else {
                        "unknown panic".to_string()
                    };

                    // Phase 195: Use unified trace
                    trace::trace().debug(
                        "router",
                        &format!(
                            "JoinIR lowering failed for {}: {}, falling back to legacy",
                            func_name, panic_msg
                        ),
                    );
                    // Return None to fall back to legacy LoopBuilder
                    return Ok(None);
                }
            }
        };
        // Phase 49-3 MVP: Use empty meta map (full if-analysis is Phase 40+ territory)
        let join_meta = JoinFuncMetaMap::new();

        // Phase 195: Use unified trace
        trace::trace().joinir_stats(
            "router",
            join_module.functions.len(),
            join_module
                .functions
                .values()
                .map(|f| f.body.len())
                .sum(),
        );

        // Step 4: Convert JoinModule to MIR
        let mir_module = convert_join_module_to_mir_with_meta(&join_module, &join_meta)
            .map_err(|e| format!("JoinIR→MIR conversion failed: {}", e.message))?;

        // Phase 195: Use unified trace for MIR module stats
        if trace::trace().is_joinir_enabled() {
            trace::trace().debug(
                "router",
                &format!("MirModule has {} functions", mir_module.functions.len()),
            );
            for (name, func) in &mir_module.functions {
                trace::trace().debug(
                    "router",
                    &format!(
                        "  - {}: {} blocks, entry={:?}",
                        name,
                        func.blocks.len(),
                        func.entry_block
                    ),
                );
                // Phase 189: Debug - show block contents
                for (block_id, block) in &func.blocks {
                    trace::trace().blocks(
                        "router",
                        &format!("Block {:?}: {} instructions", block_id, block.instructions.len()),
                    );
                    for (i, inst) in block.instructions.iter().enumerate() {
                        trace::trace().instructions("router", &format!("[{}] {:?}", i, inst));
                    }
                    if let Some(ref term) = block.terminator {
                        trace::trace().instructions("router", &format!("terminator: {:?}", term));
                    }
                }
            }
        }

        // Step 5: Merge MIR blocks into current_function
        // For Phase 49-3, we'll use a simplified approach:
        // - Add generated blocks to current_function
        // - Jump from current_block to the entry of generated loop
        // - The loop exit becomes the new current_block
        // Phase 188-Impl-3: Pass None for boundary (legacy path without boundary)
        // Phase 189: Discard exit PHI result (legacy path doesn't need it)
        let _ = self.merge_joinir_mir_blocks(&mir_module, None, debug)?;

        // Return void for now (loop doesn't have a meaningful return value in this context)
        let void_val = self.next_value_id();
        self.emit_instruction(MirInstruction::Const {
            dst: void_val,
            value: ConstValue::Void,
        })?;

        Ok(Some(void_val))
    }
}