use super::super::NyashRunner;
use crate::{
    backend::MirInterpreter,
    box_factory::{BoxFactory, RuntimeError},
    core::model::BoxDeclaration as CoreBoxDecl,
    instance_v2::InstanceBox,
    mir::MirCompiler,
    parser::NyashParser,
};
use std::sync::{Arc, RwLock};
use std::{fs, process};

impl NyashRunner {
    /// Lightweight VM fallback using the in-crate MIR interpreter.
    /// - Respects using preprocessing done earlier in the pipeline
    /// - Relies on global plugin host initialized by runner
    pub(crate) fn execute_vm_fallback_interpreter(&self, filename: &str) {
        // Note: hv1 direct route is now handled at main.rs entry point (before plugin initialization).
        // This function is only called after plugin initialization has already occurred.

        // Read source
        let code = match fs::read_to_string(filename) {
            Ok(s) => s,
            Err(e) => {
                eprintln!("❌ Error reading file {}: {}", filename, e);
                process::exit(1);
            }
        };

        let trace = crate::config::env::cli_verbose()
            || crate::config::env::env_bool("NYASH_RESOLVE_TRACE");

        // Unified using/prelude handling (SSOT, parity with vm.rs):
        // - resolve_prelude_paths_profiled で preludes を発見
        // - merge_prelude_text で text-merge（.hako は AST parse しない）
        let mut code2 = if crate::config::env::enable_using() {
            match crate::runner::modes::common_util::resolve::resolve_prelude_paths_profiled(
                self, &code, filename,
            ) {
                Ok((_, prelude_paths)) => {
                    if !prelude_paths.is_empty() {
                        match crate::runner::modes::common_util::resolve::merge_prelude_text(
                            self, &code, filename,
                        ) {
                            Ok(merged) => {
                                if trace {
                                    eprintln!(
                                        "[using/text-merge] preludes={} (vm-fallback)",
                                        prelude_paths.len()
                                    );
                                }
                                merged
                            }
                            Err(e) => {
                                eprintln!("❌ {}", e);
                                process::exit(1);
                            }
                        }
                    } else {
                        code.clone()
                    }
                }
                Err(e) => {
                    eprintln!("❌ {}", e);
                    process::exit(1);
                }
            }
        } else {
            // using disabled: detect and fail fast if present
            if code.contains("\nusing ") || code.trim_start().starts_with("using ") {
                eprintln!(
                    "❌ using: prelude merge is disabled in this profile. Enable NYASH_USING_AST=1 or remove 'using' lines."
                );
                process::exit(1);
            }
            code
        };

        // Dev sugar pre-expand: @name = expr → local name = expr
        code2 = crate::runner::modes::common_util::resolve::preexpand_at_local(&code2);

        // Hako-friendly normalize
        if crate::runner::modes::common_util::hako::looks_like_hako_code(&code2)
            || filename.ends_with(".hako")
        {
            code2 = crate::runner::modes::common_util::hako::strip_local_decl(&code2);
        }

        if trace && crate::config::env::parser_stage3_enabled() {
            eprintln!(
                "[vm-fallback] Stage-3: enabled (NYASH_FEATURES/legacy env) for {}",
                filename
            );
        }

        // Fail‑Fast (opt‑in): Hako 構文を Nyash VM 経路で実行しない
        // 目的: .hako は Hakorune VM、MIR は Core/LLVM に役割分離するためのガード
        {
            let on = crate::runner::modes::common_util::hako::fail_fast_on_hako();
            if on {
                let s = code2.as_str();
                let hako_like = s.contains("static box ")
                    || s.contains("using selfhost.")
                    || s.contains("using hakorune.");
                if hako_like {
                    eprintln!(
                        "❌ Hako-like source detected in Nyash VM path. Use Hakorune VM (v1 dispatcher) or Core/LLVM for MIR.\n   hint: set HAKO_VERIFY_PRIMARY=hakovm in verify path"
                    );
                    process::exit(1);
                }
            }
        }

        // Parse main code
        let main_ast = match NyashParser::parse_from_string(&code2) {
            Ok(ast) => ast,
            Err(e) => {
                crate::runner::modes::common_util::diag::print_parse_error_with_context(
                    filename, &code2, &e,
                );
                process::exit(1);
            }
        };
        // No AST preludes (text path or no using) → use the parsed main AST as-is
        let ast_combined = main_ast;
        // Optional: dump AST statement kinds for quick diagnostics
        if std::env::var("NYASH_AST_DUMP").ok().as_deref() == Some("1") {
            use nyash_rust::ast::ASTNode;
            eprintln!("[ast] dump start (vm-fallback)");
            if let ASTNode::Program { statements, .. } = &ast_combined {
                for (i, st) in statements.iter().enumerate().take(50) {
                    let kind = match st {
                        ASTNode::BoxDeclaration {
                            is_static, name, ..
                        } => {
                            if *is_static {
                                format!("StaticBox({})", name)
                            } else {
                                format!("Box({})", name)
                            }
                        }
                        ASTNode::FunctionDeclaration { name, .. } => format!("FuncDecl({})", name),
                        ASTNode::FunctionCall { name, .. } => format!("FuncCall({})", name),
                        ASTNode::MethodCall { method, .. } => format!("MethodCall({})", method),
                        ASTNode::ScopeBox { .. } => "ScopeBox".to_string(),
                        ASTNode::ImportStatement { path, .. } => format!("Import({})", path),
                        ASTNode::UsingStatement { namespace_name, .. } => {
                            format!("Using({})", namespace_name)
                        }
                        _ => format!("{:?}", st),
                    };
                    eprintln!("[ast] {}: {}", i, kind);
                }
            }
            eprintln!("[ast] dump end");
        }
        let ast = crate::r#macro::maybe_expand_and_dump(&ast_combined, false);

        // Minimal user-defined Box support (Option A):
        // Collect BoxDeclaration entries from AST and register a lightweight
        // factory into the unified registry so `new UserBox()` works on the
        // VM fallback path as well.
        {
            use nyash_rust::ast::ASTNode;

            // Collect user-defined (non-static) box declarations at program level.
            // Additionally, record static box names so we can alias
            // `StaticBoxName` -> `StaticBoxNameInstance` when such a
            // concrete instance box exists (common pattern in libs).
            let mut nonstatic_decls: std::collections::HashMap<String, CoreBoxDecl> =
                std::collections::HashMap::new();
            let mut static_names: Vec<String> = Vec::new();
            if let ASTNode::Program { statements, .. } = &ast {
                for st in statements {
                    if let ASTNode::BoxDeclaration {
                        name,
                        fields,
                        public_fields,
                        private_fields,
                        methods,
                        constructors,
                        init_fields,
                        weak_fields,
                        is_interface,
                        extends,
                        implements,
                        type_parameters,
                        is_static,
                        ..
                    } = st
                    {
                        if *is_static {
                            static_names.push(name.clone());
                            continue; // modules/static boxes are not user-instantiable directly
                        }
                        let decl = CoreBoxDecl {
                            name: name.clone(),
                            fields: fields.clone(),
                            public_fields: public_fields.clone(),
                            private_fields: private_fields.clone(),
                            methods: methods.clone(),
                            constructors: constructors.clone(),
                            init_fields: init_fields.clone(),
                            weak_fields: weak_fields.clone(),
                            is_interface: *is_interface,
                            extends: extends.clone(),
                            implements: implements.clone(),
                            type_parameters: type_parameters.clone(),
                        };
                        nonstatic_decls.insert(name.clone(), decl);
                    }
                }
            }
            // Build final map with optional aliases for StaticName -> StaticNameInstance
            let mut decls = nonstatic_decls.clone();
            for s in static_names.into_iter() {
                let inst = format!("{}Instance", s);
                if let Some(d) = nonstatic_decls.get(&inst) {
                    decls.insert(s, d.clone());
                }
            }

            if !decls.is_empty() {
                // Inline factory: minimal User factory backed by collected declarations
                struct InlineUserBoxFactory {
                    decls: Arc<RwLock<std::collections::HashMap<String, CoreBoxDecl>>>,
                }
                impl BoxFactory for InlineUserBoxFactory {
                    fn create_box(
                        &self,
                        name: &str,
                        args: &[Box<dyn crate::box_trait::NyashBox>],
                    ) -> Result<Box<dyn crate::box_trait::NyashBox>, RuntimeError>
                    {
                        let guard = self.decls.read().unwrap();
                        let opt = guard.get(name).cloned();
                        let decl = match opt {
                            Some(d) => {
                                drop(guard);
                                d
                            }
                            None => {
                                // Quick Win 1: Show available boxes for easier debugging
                                let mut available: Vec<_> = guard.keys().cloned().collect();
                                available.sort();
                                drop(guard);
                                let hint = if available.is_empty() {
                                    "No user-defined boxes available".to_string()
                                } else if available.len() <= 10 {
                                    format!("Available: {}", available.join(", "))
                                } else {
                                    format!(
                                        "Available ({} boxes): {}, ...",
                                        available.len(),
                                        available[..10].join(", ")
                                    )
                                };
                                return Err(RuntimeError::InvalidOperation {
                                    message: format!("Unknown Box type: {}. {}", name, hint),
                                });
                            }
                        };
                        let mut inst = InstanceBox::from_declaration(
                            decl.name.clone(),
                            decl.fields.clone(),
                            decl.methods.clone(),
                        );
                        let _ = inst.init(args);
                        Ok(Box::new(inst))
                    }

                    fn box_types(&self) -> Vec<&str> {
                        vec![]
                    }

                    fn is_available(&self) -> bool {
                        true
                    }

                    fn factory_type(&self) -> crate::box_factory::FactoryType {
                        crate::box_factory::FactoryType::User
                    }
                }
                let factory = InlineUserBoxFactory {
                    decls: Arc::new(RwLock::new(decls)),
                };
                crate::runtime::unified_registry::register_user_defined_factory(Arc::new(factory));
            }
        }
        let mut compiler = MirCompiler::with_options(!self.config.no_optimize);
        let compile = match crate::runner::modes::common_util::source_hint::compile_with_source_hint(
            &mut compiler,
            ast,
            Some(filename),
        ) {
            Ok(c) => c,
            Err(e) => {
                eprintln!("❌ MIR compilation error: {}", e);
                process::exit(1);
            }
        };

        // Optional barrier-elision for parity with VM path
        let mut module_vm = compile.module.clone();
        if crate::config::env::env_bool("NYASH_VM_ESCAPE_ANALYSIS") {
            let removed = crate::mir::passes::escape::escape_elide_barriers_vm(&mut module_vm);
            if removed > 0 {
                crate::cli_v!(
                    "[VM-fallback] escape_elide_barriers: removed {} barriers",
                    removed
                );
            }
        }

        // Optional: dump MIR for diagnostics (parity with vm path)
        // Phase 25.1: File dump for offline analysis (ParserBox等)
        if let Ok(path) = std::env::var("RUST_MIR_DUMP_PATH") {
            if let Ok(mut f) = std::fs::File::create(&path) {
                let p = crate::mir::MirPrinter::new();
                let _ = std::io::Write::write_all(&mut f, p.print_module(&module_vm).as_bytes());
                eprintln!("[vm-fallback] MIR dumped to: {}", path);
            }
        }
        // Existing: NYASH_VM_DUMP_MIR dumps to stderr
        if crate::config::env::env_bool("NYASH_VM_DUMP_MIR") {
            let p = crate::mir::MirPrinter::new();
            eprintln!("{}", p.print_module(&module_vm));
        }

        // Execute via MIR interpreter
        let mut vm = MirInterpreter::new();
        // Centralized plugin guard (non-strict by default on fallback route)
        crate::runner::modes::common_util::plugin_guard::check_and_report(
            false,
            crate::config::env::env_bool("NYASH_JSON_ONLY"),
            "vm-fallback",
        );
        // Optional: verify MIR before execution (dev-only)
        if crate::config::env::env_bool("NYASH_VM_VERIFY_MIR") {
            let mut verifier = crate::mir::verification::MirVerifier::new();
            for (name, func) in module_vm.functions.iter() {
                if let Err(errors) = verifier.verify_function(func) {
                    if !errors.is_empty() {
                        eprintln!("[vm-verify] function: {}", name);
                        for er in errors {
                            eprintln!("  • {}", er);
                        }
                    }
                }
            }
        }
        if std::env::var("NYASH_DUMP_FUNCS").ok().as_deref() == Some("1") {
            eprintln!("[vm] functions available:");
            for k in module_vm.functions.keys() {
                eprintln!("  - {}", k);
            }
        }
        match vm.execute_module(&module_vm) {
            Ok(ret) => {
                use crate::box_trait::{BoolBox, IntegerBox};

                // Extract exit code from return value
                let exit_code = if let Some(ib) = ret.as_any().downcast_ref::<IntegerBox>() {
                    ib.value as i32
                } else if let Some(bb) = ret.as_any().downcast_ref::<BoolBox>() {
                    if bb.value {
                        1
                    } else {
                        0
                    }
                } else {
                    // For non-integer/bool returns, default to 0 (success)
                    0
                };

                // Exit with the return value as exit code
                process::exit(exit_code);
            }
            Err(e) => {
                eprintln!("❌ VM fallback error: {}", e);
                process::exit(1);
            }
        }
    }
}

impl NyashRunner {
    /// Small helper to continue fallback execution once AST is prepared
    #[allow(dead_code)]
    fn execute_vm_fallback_from_ast(&self, filename: &str, ast: nyash_rust::ast::ASTNode) {
        use crate::{
            backend::MirInterpreter,
            box_factory::{BoxFactory, RuntimeError},
            core::model::BoxDeclaration as CoreBoxDecl,
            instance_v2::InstanceBox,
            mir::MirCompiler,
        };
        use std::process;
        use std::sync::{Arc, RwLock};

        // Macro expand (if enabled)
        let ast = crate::r#macro::maybe_expand_and_dump(&ast, false);
        // Minimal user-defined Box support (inline factory)
        {
            use nyash_rust::ast::ASTNode;
            let mut nonstatic_decls: std::collections::HashMap<String, CoreBoxDecl> =
                std::collections::HashMap::new();
            let mut static_names: Vec<String> = Vec::new();
            if let ASTNode::Program { statements, .. } = &ast {
                for st in statements {
                    if let ASTNode::BoxDeclaration {
                        name,
                        fields,
                        public_fields,
                        private_fields,
                        methods,
                        constructors,
                        init_fields,
                        weak_fields,
                        is_interface,
                        extends,
                        implements,
                        type_parameters,
                        is_static,
                        ..
                    } = st
                    {
                        if *is_static {
                            static_names.push(name.clone());
                            continue;
                        }
                        let decl = CoreBoxDecl {
                            name: name.clone(),
                            fields: fields.clone(),
                            public_fields: public_fields.clone(),
                            private_fields: private_fields.clone(),
                            methods: methods.clone(),
                            constructors: constructors.clone(),
                            init_fields: init_fields.clone(),
                            weak_fields: weak_fields.clone(),
                            is_interface: *is_interface,
                            extends: extends.clone(),
                            implements: implements.clone(),
                            type_parameters: type_parameters.clone(),
                        };
                        nonstatic_decls.insert(name.clone(), decl);
                    }
                }
            }
            let mut decls = nonstatic_decls.clone();
            for s in static_names.into_iter() {
                let inst = format!("{}Instance", s);
                if let Some(d) = nonstatic_decls.get(&inst) {
                    decls.insert(s, d.clone());
                }
            }
            if !decls.is_empty() {
                struct InlineUserBoxFactory {
                    decls: Arc<RwLock<std::collections::HashMap<String, CoreBoxDecl>>>,
                }
                impl BoxFactory for InlineUserBoxFactory {
                    fn create_box(
                        &self,
                        name: &str,
                        args: &[Box<dyn crate::box_trait::NyashBox>],
                    ) -> Result<Box<dyn crate::box_trait::NyashBox>, RuntimeError>
                    {
                        let guard = self.decls.read().unwrap();
                        let opt = guard.get(name).cloned();
                        let decl = match opt {
                            Some(d) => {
                                drop(guard);
                                d
                            }
                            None => {
                                // Quick Win 1: Show available boxes for easier debugging
                                let mut available: Vec<_> = guard.keys().cloned().collect();
                                available.sort();
                                drop(guard);
                                let hint = if available.is_empty() {
                                    "No user-defined boxes available".to_string()
                                } else if available.len() <= 10 {
                                    format!("Available: {}", available.join(", "))
                                } else {
                                    format!(
                                        "Available ({} boxes): {}, ...",
                                        available.len(),
                                        available[..10].join(", ")
                                    )
                                };
                                return Err(RuntimeError::InvalidOperation {
                                    message: format!("Unknown Box type: {}. {}", name, hint),
                                });
                            }
                        };
                        let mut inst = InstanceBox::from_declaration(
                            decl.name.clone(),
                            decl.fields.clone(),
                            decl.methods.clone(),
                        );
                        let _ = inst.init(args);
                        Ok(Box::new(inst))
                    }

                    fn box_types(&self) -> Vec<&str> {
                        vec![]
                    }
                    fn is_available(&self) -> bool {
                        true
                    }
                    fn factory_type(&self) -> crate::box_factory::FactoryType {
                        crate::box_factory::FactoryType::User
                    }
                }
                let factory = InlineUserBoxFactory {
                    decls: Arc::new(RwLock::new(decls)),
                };
                crate::runtime::unified_registry::register_user_defined_factory(Arc::new(factory));
            }
        }
        // Compile to MIR and execute via interpreter
        let mut compiler = MirCompiler::with_options(!self.config.no_optimize);
        let module = match crate::runner::modes::common_util::source_hint::compile_with_source_hint(
            &mut compiler,
            ast,
            Some(filename),
        ) {
            Ok(r) => r.module,
            Err(e) => {
                eprintln!("❌ MIR compilation error: {}", e);
                process::exit(1);
            }
        };
        let mut interp = MirInterpreter::new();
        match interp.execute_module(&module) {
            Ok(result) => {
                use nyash_rust::box_trait::{BoolBox, IntegerBox};
                let rc = if let Some(ib) = result.as_any().downcast_ref::<IntegerBox>() {
                    ib.value as i32
                } else if let Some(bb) = result.as_any().downcast_ref::<BoolBox>() {
                    if bb.value {
                        1
                    } else {
                        0
                    }
                } else {
                    0
                };
                // For C‑API pure pipeline, suppress "RC:" text to keep last line = exe path
                let capi = std::env::var("NYASH_LLVM_USE_CAPI").ok().as_deref() == Some("1");
                let pure = std::env::var("HAKO_CAPI_PURE").ok().as_deref() == Some("1");
                if !(capi && pure) {
                    println!("RC: {}", rc);
                }
                process::exit(rc);
            }
            Err(e) => {
                eprintln!("❌ VM fallback runtime error: {}", e);
                process::exit(1);
            }
        }
    }
}
