assura 0.4.0

use super::*;

// `assura infer <rust_file>` -- generate skeleton Assura contracts
// ---------------------------------------------------------------------------

pub(crate) fn run_infer(
    filename: &str,
    function_filter: Option<&str>,
    output_path: Option<&str>,
    dry_run: bool,
    focus: Option<&str>,
    output_mode: assura_config::OutputMode,
) {
    let source = fs::read_to_string(filename).unwrap_or_else(|e| {
        if output_mode == assura_config::OutputMode::Json {
            let report = serde_json::json!({
                "ok": false,
                "success": false,
                "file": filename,
                "error": format!("{e}"),
                "message": format!("{filename}: {e}"),
            });
            println!("{}", serde_json::to_string_pretty(&report).unwrap());
        } else {
            eprintln!("Error: {filename}: {e}");
        }
        process::exit(2);
    });

    // Parse focus patterns
    let focus_patterns: Vec<&str> = focus
        .map(|f| f.split(',').map(str::trim).collect())
        .unwrap_or_default();

    // Try heuristic-based inference using syn parser (for .rs files)
    if filename.ends_with(".rs") {
        run_infer_heuristic(
            filename,
            &source,
            &focus_patterns,
            dry_run,
            output_path,
            output_mode,
        );
        return;
    }

    // Legacy path: generate .assura bind skeletons from Rust source
    let signatures = extract_rust_fn_signatures(&source);

    if signatures.is_empty() {
        if output_mode == assura_config::OutputMode::Json {
            println!(
                "{}",
                serde_json::to_string_pretty(&serde_json::json!({
                    "file": filename,
                    "function_count": 0,
                    "suggestion_count": 0,
                    "suggestions": [],
                    "message": format!("No public function signatures found in {filename}"),
                    "success": false,
                }))
                .unwrap()
            );
        } else {
            eprintln!("No public function signatures found in {filename}");
        }
        process::exit(1);
    }

    let filtered: Vec<&RustFnSig> = if let Some(name) = function_filter {
        let matches: Vec<_> = signatures.iter().filter(|s| s.name == name).collect();
        if matches.is_empty() {
            if output_mode == assura_config::OutputMode::Json {
                let names: Vec<_> = signatures
                    .iter()
                    .filter(|s| s.is_pub)
                    .map(|s| s.name.as_str())
                    .collect();
                println!(
                    "{}",
                    serde_json::to_string_pretty(&serde_json::json!({
                        "file": filename,
                        "function_count": 0,
                        "suggestion_count": 0,
                        "suggestions": [],
                        "message": format!("Function '{name}' not found in {filename}"),
                        "available": names,
                        "success": false,
                    }))
                    .unwrap()
                );
            } else {
                eprintln!("Function '{name}' not found in {filename}");
                let names: Vec<_> = signatures
                    .iter()
                    .filter(|s| s.is_pub)
                    .map(|s| s.name.as_str())
                    .collect();
                eprintln!("Available public functions: {}", names.join(", "));
            }
            process::exit(1);
        }
        matches
    } else {
        // Default: only public functions
        signatures.iter().filter(|s| s.is_pub).collect()
    };

    if filtered.is_empty() {
        if output_mode == assura_config::OutputMode::Json {
            println!(
                "{}",
                serde_json::to_string_pretty(&serde_json::json!({
                    "file": filename,
                    "function_count": 0,
                    "suggestion_count": 0,
                    "suggestions": [],
                    "message": format!("No public function signatures found in {filename}"),
                    "success": false,
                }))
                .unwrap()
            );
        } else {
            eprintln!("No public function signatures found in {filename}");
        }
        process::exit(1);
    }

    let module_path = derive_rust_module_path(filename);

    let mut out_buf = String::new();
    out_buf.push_str(&format!(
        "// Generated by: assura infer {filename}\n// Review and refine these contracts before use.\n\n"
    ));

    for sig in &filtered {
        generate_bind_skeleton(&module_path, sig, &mut out_buf);
    }

    out_buf.push_str(&format!(
        "\n// {} function(s) analyzed from {filename}\n",
        filtered.len()
    ));

    if let Some(path) = output_path {
        fs::write(path, &out_buf).unwrap_or_else(|e| {
            if output_mode == assura_config::OutputMode::Json {
                let report = serde_json::json!({
                    "ok": false,
                    "success": false,
                    "file": filename,
                    "output": path,
                    "error": format!("cannot write {path}: {e}"),
                });
                println!("{}", serde_json::to_string_pretty(&report).unwrap());
            } else {
                eprintln!("Error: cannot write {path}: {e}");
            }
            process::exit(2);
        });
        if output_mode == assura_config::OutputMode::Json {
            let report = serde_json::json!({
                "ok": true,
                "success": true,
                "file": filename,
                "output": path,
                "function_count": filtered.len(),
            });
            println!("{}", serde_json::to_string_pretty(&report).unwrap());
        } else {
            eprintln!("Wrote {} contract(s) to {path}", filtered.len());
        }
    } else if output_mode == assura_config::OutputMode::Json {
        // Source is the product for non-.rs legacy path when writing to stdout.
        print!("{out_buf}");
    } else {
        print!("{out_buf}");
    }
}

/// A suggested contract annotation for a function.
pub(crate) struct InferSuggestion {
    line: usize,
    fn_name: String,
    /// Parameter names from the Rust signature (for skeleton input clauses).
    params: Vec<String>,
    annotations: Vec<String>,
    pattern: String,
}

/// Run heuristic-based inference on a Rust source file.
///
/// Detects common patterns that suggest contracts:
/// - Division operations: suggest `@requires divisor != 0`
/// - Array/slice indexing: suggest `@requires index < len`
/// - `.unwrap()` calls: suggest `@requires` for `is_some()`/`is_ok()`
/// - Unsafe blocks: note for manual review
pub(crate) fn run_infer_heuristic(
    filename: &str,
    source: &str,
    focus: &[&str],
    dry_run: bool,
    output_path: Option<&str>,
    output_mode: assura_config::OutputMode,
) {
    let mut suggestions = Vec::new();

    // Parse with syn for precise analysis
    let file = match syn::parse_file(source) {
        Ok(f) => f,
        Err(e) => {
            if output_mode == assura_config::OutputMode::Json {
                println!(
                    "{}",
                    serde_json::to_string_pretty(&serde_json::json!({
                        "file": filename,
                        "function_count": 0,
                        "suggestion_count": 0,
                        "suggestions": [],
                        "message": format!("Error parsing {filename}: {e}"),
                        "success": false,
                    }))
                    .unwrap()
                );
            } else {
                eprintln!("Error parsing {filename}: {e}");
            }
            process::exit(1);
        }
    };

    for item in &file.items {
        match item {
            syn::Item::Fn(func) => {
                let suggs = analyze_function_body(func, source, focus);
                suggestions.extend(suggs);
            }
            syn::Item::Impl(imp) => {
                for impl_item in &imp.items {
                    if let syn::ImplItem::Fn(method) = impl_item {
                        let suggs = analyze_method_body(method, source, focus);
                        suggestions.extend(suggs);
                    }
                }
            }
            _ => {}
        }
    }

    if suggestions.is_empty() {
        let signatures = extract_rust_fn_signatures(source);
        let public: Vec<_> = signatures.iter().filter(|s| s.is_pub).collect();
        // With -o, still emit checkable bind skeletons for public functions so
        // `assura infer src/lib.rs -o contracts.assura` works on clean code
        // (no unwrap/div/index risk patterns). Without -o, keep the old message.
        if output_path.is_some() && !dry_run && focus.is_empty() && !public.is_empty() {
            let module_path = derive_rust_module_path(filename);
            let mut out_buf = String::new();
            out_buf.push_str(&format!(
                "// Generated by: assura infer {filename}\n// No risk-pattern hits; skeleton binds for all public functions.\n// Review and refine these contracts before use.\n\n"
            ));
            for sig in &public {
                generate_bind_skeleton(&module_path, sig, &mut out_buf);
            }
            if let Some(path) = output_path {
                fs::write(path, &out_buf).unwrap_or_else(|e| {
                    if output_mode == assura_config::OutputMode::Json {
                        let report = serde_json::json!({
                            "ok": false,
                            "success": false,
                            "file": filename,
                            "output": path,
                            "error": format!("cannot write {path}: {e}"),
                        });
                        println!("{}", serde_json::to_string_pretty(&report).unwrap());
                    } else {
                        eprintln!("Error writing {path}: {e}");
                    }
                    process::exit(2);
                });
                if output_mode == assura_config::OutputMode::Json {
                    println!(
                        "{}",
                        serde_json::to_string_pretty(&serde_json::json!({
                            "file": filename,
                            "output": path,
                            "function_count": public.len(),
                            "suggestion_count": 0,
                            "status": "ok",
                            "message": "no risk-pattern hits; wrote skeleton binds",
                            "functions": public.iter().map(|s| &s.name).collect::<Vec<_>>(),
                        }))
                        .unwrap()
                    );
                } else {
                    eprintln!(
                        "Wrote {} skeleton contract(s) to {path} (no risk-pattern hits)",
                        public.len()
                    );
                }
            }
            return;
        }
        if output_mode == assura_config::OutputMode::Json {
            let report = serde_json::json!({
                "file": filename,
                "suggestion_count": 0,
                "function_count": public.len(),
                "functions": public.iter().map(|s| &s.name).collect::<Vec<_>>(),
                "suggestions": [],
                "message": format!("No contract suggestions for {filename}"),
                "focus": focus,
                "success": true,
            });
            println!("{}", serde_json::to_string_pretty(&report).unwrap());
        } else {
            println!("No contract suggestions for {filename}");
            if !focus.is_empty() {
                println!("  (filtered by: {})", focus.join(", "));
            }
        }
        return;
    }

    // Format output. With --dry-run (or stdout), emit review comments.
    // With -o and without --dry-run, emit skeleton .assura contracts so the
    // file is loadable by `assura check` (not just commented suggestions).
    let emit_contracts = output_path.is_some() && !dry_run;
    let mut output = String::new();
    if emit_contracts {
        output.push_str(&format!(
            "// Generated by: assura infer {filename}\n// Review and refine before use.\n\n"
        ));
        for s in &suggestions {
            output.push_str(&format!("// From {filename}:{} [{}]\n", s.line, s.pattern));
            output.push_str(&format!(
                "contract {} {{\n",
                sanitize_contract_name(&s.fn_name)
            ));
            if s.params.is_empty() {
                output.push_str("    input(x: Int)\n");
            } else {
                let parts: Vec<String> = s.params.iter().map(|p| format!("{p}: Int")).collect();
                output.push_str(&format!("    input({})\n", parts.join(", ")));
            }
            let mut has_clause = false;
            for ann in &s.annotations {
                let body = ann
                    .trim()
                    .trim_start_matches('/')
                    .trim()
                    .trim_start_matches('@');
                // Skip pure REVIEW comments
                if body.starts_with("REVIEW") || body.starts_with("// REVIEW") {
                    continue;
                }
                if let Some(idx) = body.find("requires") {
                    let rest = body[idx + "requires".len()..].trim();
                    // Drop trailing comments
                    let rest = rest.split("//").next().unwrap_or(rest).trim();
                    if !rest.is_empty() && !rest.contains('<') {
                        output.push_str(&format!("    requires {{ {rest} }}\n"));
                        has_clause = true;
                    }
                } else if let Some(idx) = body.find("ensures") {
                    let rest = body[idx + "ensures".len()..].trim();
                    let rest = rest.split("//").next().unwrap_or(rest).trim();
                    if !rest.is_empty() && !rest.contains('<') {
                        output.push_str(&format!("    ensures {{ {rest} }}\n"));
                        has_clause = true;
                    }
                }
            }
            if !has_clause {
                output.push_str("    requires { true }\n");
            }
            output.push_str("}\n\n");
        }
    } else {
        let mode = if dry_run { " --dry-run" } else { "" };
        output.push_str(&format!(
            "// Contract suggestions for {filename}\n// Generated by: assura infer{mode}\n// Review each suggestion before accepting.\n\n"
        ));
        for s in &suggestions {
            output.push_str(&format!(
                "// [{pattern}] {fn_name} (line {line})\n",
                pattern = s.pattern,
                fn_name = s.fn_name,
                line = s.line
            ));
            for ann in &s.annotations {
                output.push_str(&format!("//   {ann}\n"));
            }
            output.push('\n');
        }
        output.push_str(&format!(
            "// {} suggestion(s) for {} function(s)\n",
            suggestions
                .iter()
                .map(|s| s.annotations.len())
                .sum::<usize>(),
            suggestions.len()
        ));
    }

    let ann_count: usize = suggestions.iter().map(|s| s.annotations.len()).sum();

    if output_mode == assura_config::OutputMode::Json && (dry_run || output_path.is_none()) {
        let report = serde_json::json!({
            "file": filename,
            "suggestion_count": ann_count,
            "function_count": suggestions.len(),
            "suggestions": suggestions.iter().map(|s| serde_json::json!({
                "function": s.fn_name,
                "line": s.line,
                "pattern": s.pattern,
                "params": s.params,
                "annotations": s.annotations,
            })).collect::<Vec<_>>(),
            "text": output,
        });
        println!("{}", serde_json::to_string_pretty(&report).unwrap());
        return;
    }

    if dry_run || output_path.is_none() {
        print!("{output}");
    }
    if let Some(path) = output_path
        && !dry_run
    {
        fs::write(path, &output).unwrap_or_else(|e| {
            if output_mode == assura_config::OutputMode::Json {
                let report = serde_json::json!({
                    "ok": false,
                    "success": false,
                    "file": filename,
                    "output": path,
                    "error": format!("cannot write {path}: {e}"),
                });
                println!("{}", serde_json::to_string_pretty(&report).unwrap());
            } else {
                eprintln!("Error writing {path}: {e}");
            }
            process::exit(2);
        });
        if output_mode == assura_config::OutputMode::Json {
            println!(
                "{}",
                serde_json::json!({
                    "file": filename,
                    "output": path,
                    "function_count": suggestions.len(),
                    "suggestion_count": ann_count,
                    "status": "ok",
                })
            );
        } else {
            eprintln!("Wrote {} contract skeleton(s) to {path}", suggestions.len());
        }
    }

    if output_mode != assura_config::OutputMode::Json {
        println!(
            "\n{ann_count} suggestion(s) found across {} function(s)",
            suggestions.len()
        );
    }
}

fn sanitize_contract_name(name: &str) -> String {
    let mut out = String::new();
    for (i, c) in name.chars().enumerate() {
        if c.is_ascii_alphanumeric() || c == '_' {
            if i == 0 && c.is_ascii_digit() {
                out.push('_');
            }
            out.push(c);
        } else {
            out.push('_');
        }
    }
    if out.is_empty() {
        "Inferred".into()
    } else {
        // Contract names are typically PascalCase; capitalize first letter.
        let mut chars = out.chars();
        match chars.next() {
            Some(f) => f.to_uppercase().collect::<String>() + chars.as_str(),
            None => "Inferred".into(),
        }
    }
}

/// Analyze a free function body for contract suggestions.
pub(crate) fn analyze_function_body(
    func: &syn::ItemFn,
    source: &str,
    focus: &[&str],
) -> Vec<InferSuggestion> {
    let name = func.sig.ident.to_string();
    let body_str = extract_block_text(&func.block, source);
    let line = func.sig.fn_token.span.start().line + 1;
    let params = extract_param_names(&func.sig);
    analyze_body_text(&name, &body_str, line, &params, focus)
}

/// Analyze a method body for contract suggestions.
pub(crate) fn analyze_method_body(
    method: &syn::ImplItemFn,
    source: &str,
    focus: &[&str],
) -> Vec<InferSuggestion> {
    let name = method.sig.ident.to_string();
    let body_str = extract_block_text(&method.block, source);
    let line = method.sig.fn_token.span.start().line + 1;
    let params = extract_param_names(&method.sig);
    analyze_body_text(&name, &body_str, line, &params, focus)
}

/// Extract the text of a block from source using span info.
pub(crate) fn extract_block_text(block: &syn::Block, _source: &str) -> String {
    use quote::ToTokens;
    block.to_token_stream().to_string()
}

/// Extract parameter names from a function signature.
pub(crate) fn extract_param_names(sig: &syn::Signature) -> Vec<String> {
    sig.inputs
        .iter()
        .filter_map(|arg| match arg {
            syn::FnArg::Typed(pt) => {
                use quote::ToTokens;
                Some(pt.pat.to_token_stream().to_string())
            }
            syn::FnArg::Receiver(_) => None,
        })
        .collect()
}

/// Analyze function body text for patterns that suggest contracts.
pub(crate) fn analyze_body_text(
    fn_name: &str,
    body: &str,
    line: usize,
    params: &[String],
    focus: &[&str],
) -> Vec<InferSuggestion> {
    let mut suggestions = Vec::new();
    let focus_all = focus.is_empty();

    // Pattern: division by a parameter
    if (focus_all || focus.contains(&"division")) && body.contains('/') {
        for param in params {
            if body.contains(&format!("/ {param}"))
                || body.contains(&format!("/{param}"))
                || body.contains(&format!("% {param}"))
            {
                suggestions.push(InferSuggestion {
                    line,
                    fn_name: fn_name.to_string(),
                    params: params.to_vec(),
                    annotations: vec![format!("/// @requires {param} != 0")],
                    pattern: "division".to_string(),
                });
            }
        }
    }

    // Pattern: .unwrap() calls (tokenized output may have spaces: ". unwrap ()")
    if (focus_all || focus.contains(&"unwrap"))
        && (body.contains(".unwrap()") || body.contains(". unwrap ()"))
    {
        suggestions.push(InferSuggestion {
            line,
            fn_name: fn_name.to_string(),
            params: params.to_vec(),
            annotations: vec![
                "/// @requires <value>.is_some() // or .is_ok()".to_string(),
                "// REVIEW: .unwrap() panics on None/Err".to_string(),
            ],
            pattern: "unwrap".to_string(),
        });
    }

    // Pattern: array/slice indexing with parameter
    // Tokenized output may have spaces: "items [idx]" or "[idx]"
    if (focus_all || focus.contains(&"index")) && body.contains('[') {
        for param in params {
            if body.contains(&format!("[{param}]"))
                || body.contains(&format!("[ {param} ]"))
                || body.contains(&format!("[{param} ]"))
                || body.contains(&format!("[ {param}]"))
            {
                suggestions.push(InferSuggestion {
                    line,
                    fn_name: fn_name.to_string(),
                    params: params.to_vec(),
                    annotations: vec![format!("/// @requires {param} < <collection>.len()")],
                    pattern: "index".to_string(),
                });
            }
        }
    }

    // Pattern: unsafe blocks (keyword may appear in tokenized output)
    if (focus_all || focus.contains(&"unsafe"))
        && (body.contains("unsafe") || body.contains("unsafe {"))
    {
        suggestions.push(InferSuggestion {
            line,
            fn_name: fn_name.to_string(),
            params: params.to_vec(),
            annotations: vec![
                "// REVIEW: contains unsafe block, manual contract required".to_string(),
            ],
            pattern: "unsafe".to_string(),
        });
    }

    // Pattern: panic!/todo!/unimplemented! (tokenized: "panic !", "todo !", etc.)
    if (focus_all || focus.contains(&"panic"))
        && (body.contains("panic!")
            || body.contains("panic !")
            || body.contains("todo!")
            || body.contains("todo !")
            || body.contains("unimplemented!")
            || body.contains("unimplemented !"))
    {
        suggestions.push(InferSuggestion {
            line,
            fn_name: fn_name.to_string(),
            params: params.to_vec(),
            annotations: vec![
                "// REVIEW: contains panic!/todo!/unimplemented!, add @requires to prevent"
                    .to_string(),
            ],
            pattern: "panic".to_string(),
        });
    }

    suggestions
}

/// A parsed Rust function signature (minimal, no syn dependency).
pub(crate) struct RustFnSig {
    pub(crate) name: String,
    pub(crate) params: Vec<(String, String)>, // (name, type)
    pub(crate) return_type: String,
    pub(crate) is_pub: bool,
    /// True when the declaration includes the `unsafe` keyword.
    pub(crate) is_unsafe: bool,
}

/// Extract public function signatures from Rust source text.
///
/// This is a lightweight regex-free parser that handles common patterns.
/// It does NOT use syn (to avoid adding a heavy dependency to the CLI).
pub(crate) fn extract_rust_fn_signatures(source: &str) -> Vec<RustFnSig> {
    let mut sigs = Vec::new();
    let lines: Vec<&str> = source.lines().collect();
    let mut i = 0;

    while i < lines.len() {
        let line = lines[i].trim();

        // Strip leading modifiers to find `fn ` keyword.
        // Handles: pub fn, pub(crate) fn, pub async fn, pub const fn,
        //          pub unsafe fn, async fn, const fn, unsafe fn, etc.
        let (is_pub, is_unsafe, fn_part) = match strip_fn_prefix(line) {
            Some(triple) => triple,
            None => {
                i += 1;
                continue;
            }
        };

        // Collect full signature (may span multiple lines)
        let mut full_sig = fn_part.to_string();
        let mut j = i + 1;
        while !full_sig.contains('{') && !full_sig.contains(';') && j < lines.len() {
            full_sig.push(' ');
            full_sig.push_str(lines[j].trim());
            j += 1;
        }

        if let Some(sig) = parse_fn_signature(&full_sig, is_pub, is_unsafe) {
            sigs.push(sig);
        }

        i = j.max(i + 1);
    }

    sigs
}

/// Strip function declaration prefix and return `(is_pub, is_unsafe, rest_after_fn)`.
/// Handles all modifier combinations: pub/pub(vis), async, const, unsafe.
pub(crate) fn strip_fn_prefix(line: &str) -> Option<(bool, bool, &str)> {
    let mut rest = line;
    let mut is_pub = false;
    let mut is_unsafe = false;

    // Check for pub / pub(vis)
    if let Some(after_pub) = rest.strip_prefix("pub") {
        is_pub = true;
        rest = after_pub;
        // Handle pub(crate), pub(super), pub(in path)
        let trimmed = rest.trim_start();
        if let Some(after_paren) = trimmed.strip_prefix('(') {
            let close = after_paren.find(')')?;
            rest = &after_paren[close + 1..];
        } else {
            rest = trimmed;
        }
    }

    // Strip optional modifiers: async, const, unsafe (in any order)
    loop {
        let trimmed = rest.trim_start();
        if let Some(after) = trimmed.strip_prefix("async ") {
            rest = after;
        } else if let Some(after) = trimmed.strip_prefix("const ") {
            rest = after;
        } else if let Some(after) = trimmed.strip_prefix("unsafe ") {
            is_unsafe = true;
            rest = after;
        } else {
            rest = trimmed;
            break;
        }
    }

    // Must find `fn ` keyword
    let after_fn = rest.strip_prefix("fn ")?;
    Some((is_pub, is_unsafe, after_fn))
}

/// Parse a single function signature string like "foo(x: i64, y: &str) -> bool {"
pub(crate) fn parse_fn_signature(sig: &str, is_pub: bool, is_unsafe: bool) -> Option<RustFnSig> {
    let paren_open = sig.find('(')?;
    let raw_name = sig[..paren_open].trim();

    // Strip generic parameters: `encode<T: Serialize>` -> `encode`
    let name = if let Some(angle) = raw_name.find('<') {
        raw_name[..angle].trim().to_string()
    } else {
        raw_name.to_string()
    };

    // Skip if name contains invalid chars (macros, etc.)
    if name.is_empty() || !name.chars().all(|c| c.is_alphanumeric() || c == '_') {
        return None;
    }

    // Find matching closing paren (handle nested parens)
    let after_open = &sig[paren_open + 1..];
    let mut depth = 1i32;
    let mut close_offset = 0;
    for (i, ch) in after_open.char_indices() {
        match ch {
            '(' => depth += 1,
            ')' => {
                depth -= 1;
                if depth == 0 {
                    close_offset = i;
                    break;
                }
            }
            _ => {}
        }
    }

    let params_str = &after_open[..close_offset];
    let params = parse_param_list(params_str);

    // Extract return type
    let after_close = &after_open[close_offset + 1..];
    let return_type = if let Some(arrow_pos) = after_close.find("->") {
        let ret = after_close[arrow_pos + 2..].trim();
        // Strip trailing { or where
        let ret = ret
            .split('{')
            .next()
            .unwrap_or(ret)
            .split("where")
            .next()
            .unwrap_or(ret)
            .trim();
        ret.to_string()
    } else {
        "()".to_string()
    };

    Some(RustFnSig {
        name,
        params,
        return_type,
        is_pub,
        is_unsafe,
    })
}

/// Parse a parameter list like "x: i64, y: &str, _: bool"
pub(crate) fn parse_param_list(params: &str) -> Vec<(String, String)> {
    let params = params.trim();
    if params.is_empty() {
        return Vec::new();
    }

    let mut result = Vec::new();
    let mut depth = 0i32;
    let mut paren_depth = 0i32;
    let mut start = 0;

    // Split on commas respecting <> and ()
    let mut segments = Vec::new();
    for (i, ch) in params.char_indices() {
        match ch {
            '<' => depth += 1,
            '>' if depth > 0 => depth -= 1,
            '(' => paren_depth += 1,
            ')' if paren_depth > 0 => paren_depth -= 1,
            ',' if depth == 0 && paren_depth == 0 => {
                segments.push(&params[start..i]);
                start = i + 1;
            }
            _ => {}
        }
    }
    segments.push(&params[start..]);

    for seg in segments {
        let seg = seg.trim();
        // Skip self, &self, &mut self
        if seg == "self" || seg == "&self" || seg == "&mut self" {
            continue;
        }
        if let Some(colon_pos) = seg.find(':') {
            let name = seg[..colon_pos].trim();
            let ty = seg[colon_pos + 1..].trim();
            if !name.is_empty() {
                result.push((name.to_string(), ty.to_string()));
            }
        }
    }

    result
}

/// Derive a Rust module path from a filesystem path.
///
/// Walks up from the file looking for `Cargo.toml` to find the crate name.
/// Converts hyphens to underscores (Rust identifier convention).
/// Strips the `src/` segment and maps `lib.rs`/`mod.rs` to their parent module.
///
/// Examples:
///   `crates/assura-codegen/src/type_map.rs` -> `assura_codegen::type_map`
///   `src/lib.rs` -> `my_crate` (crate name from Cargo.toml)
///   `src/foo/bar.rs` -> `my_crate::foo::bar`
pub(crate) fn derive_rust_module_path(file_path: &str) -> String {
    let path = Path::new(file_path);

    // Find the src/ component and the crate root above it
    let components: Vec<_> = path.components().collect();
    let mut crate_name: Option<String> = None;
    let mut src_index: Option<usize> = None;

    for (i, comp) in components.iter().enumerate() {
        if comp.as_os_str() == "src" {
            src_index = Some(i);
            // Crate root is the directory containing src/
            let crate_root: std::path::PathBuf = if i > 0 {
                components[..i].iter().collect()
            } else {
                std::path::PathBuf::from(".")
            };
            // Try to read crate name from Cargo.toml
            let cargo_path = crate_root.join("Cargo.toml");
            if let Ok(content) = fs::read_to_string(&cargo_path) {
                for line in content.lines() {
                    let trimmed = line.trim();
                    if let Some(rest) = trimmed.strip_prefix("name") {
                        let rest = rest.trim_start();
                        if let Some(rest) = rest.strip_prefix('=') {
                            let rest = rest.trim();
                            let name = rest.trim_matches('"').trim_matches('\'');
                            crate_name = Some(name.replace('-', "_"));
                            break;
                        }
                    }
                }
            }
            break;
        }
    }

    let crate_segment = crate_name.unwrap_or_else(|| "crate".to_string());

    if let Some(si) = src_index {
        // Build relative path from components after src/
        if si + 1 < components.len() {
            let after_src: std::path::PathBuf = components[si + 1..].iter().collect();
            let rel_str = after_src
                .to_string_lossy()
                .trim_end_matches(".rs")
                .replace(['/', '\\'], "::");

            // lib.rs / mod.rs -> just the parent module (or crate root)
            if rel_str == "lib" || rel_str == "mod" {
                crate_segment
            } else if rel_str.ends_with("::mod") || rel_str.ends_with("::lib") {
                let trimmed = rel_str.trim_end_matches("::mod").trim_end_matches("::lib");
                format!("{crate_segment}::{trimmed}")
            } else {
                format!("{crate_segment}::{rel_str}")
            }
        } else {
            // Path ends at src/ itself (unusual)
            crate_segment
        }
    } else {
        // No src/ found; fallback: strip .rs, convert path separators, fix hyphens
        file_path
            .trim_end_matches(".rs")
            .replace('/', "::")
            .replace('-', "_")
    }
}

/// Generate a bind skeleton for a single function.
pub(crate) fn generate_bind_skeleton(module_path: &str, sig: &RustFnSig, out: &mut String) {
    use assura_codegen::type_map::rust_type_to_assura;

    let rust_path = format!("{module_path}::{}", sig.name);

    out.push_str(&format!("bind \"{}\" as {} {{\n", rust_path, sig.name));

    // Input params
    if !sig.params.is_empty() {
        out.push_str("    input(");
        let params: Vec<String> = sig
            .params
            .iter()
            .map(|(name, ty)| format!("{}: {}", name, rust_type_to_assura(ty)))
            .collect();
        out.push_str(&params.join(", "));
        out.push_str(")\n");
    }

    // Output
    let assura_ret = rust_type_to_assura(&sig.return_type);
    if assura_ret != "Unit" {
        out.push_str(&format!("    output(result: {assura_ret})\n"));
    }

    // Heuristic clause generation based on parameter and return types
    let mut has_clause = false;

    for (name, rust_ty) in &sig.params {
        let param_assura = rust_type_to_assura(rust_ty);
        if matches!(param_assura.as_str(), "Int" | "Nat" | "Float") {
            out.push_str(&format!("    requires {{ {name} >= 0 }}\n"));
            has_clause = true;
        }
    }

    if matches!(assura_ret.as_str(), "Int" | "Nat" | "Float") {
        out.push_str("    ensures { result >= 0 }\n");
        has_clause = true;
    }

    if !has_clause {
        out.push_str("    // TODO: add requires clauses (preconditions)\n");
        out.push_str("    // TODO: add ensures clauses (postconditions)\n");
    }

    out.push_str("}\n\n");
}

// ---------------------------------------------------------------------------

#[cfg(test)]
mod tests {
    use super::*;

    // ---- strip_fn_prefix ----

    #[test]
    fn strip_pub_fn() {
        let (is_pub, is_unsafe, rest) = strip_fn_prefix("pub fn foo()").unwrap();
        assert!(is_pub);
        assert!(!is_unsafe);
        assert_eq!(rest, "foo()");
    }

    #[test]
    fn strip_plain_fn() {
        let (is_pub, is_unsafe, rest) = strip_fn_prefix("fn bar()").unwrap();
        assert!(!is_pub);
        assert!(!is_unsafe);
        assert_eq!(rest, "bar()");
    }

    #[test]
    fn strip_pub_crate_fn() {
        let (is_pub, is_unsafe, rest) = strip_fn_prefix("pub(crate) fn baz()").unwrap();
        assert!(is_pub);
        assert!(!is_unsafe);
        assert_eq!(rest, "baz()");
    }

    #[test]
    fn strip_pub_async_fn() {
        let (is_pub, is_unsafe, rest) = strip_fn_prefix("pub async fn fetch()").unwrap();
        assert!(is_pub);
        assert!(!is_unsafe);
        assert_eq!(rest, "fetch()");
    }

    #[test]
    fn strip_pub_unsafe_fn() {
        let (is_pub, is_unsafe, rest) = strip_fn_prefix("pub unsafe fn danger()").unwrap();
        assert!(is_pub);
        assert!(is_unsafe);
        assert_eq!(rest, "danger()");
    }

    #[test]
    fn extract_marks_unsafe_per_function_not_file() {
        // File-level contains("unsafe") would mark clean too; we only flag
        // functions whose declaration itself has the unsafe keyword.
        let source = r#"
pub fn clean(x: i32) -> i32 { x }
pub unsafe fn danger(p: *const u8) -> u8 { *p }
pub fn also_clean() { let _ = 1; }
"#;
        let sigs = extract_rust_fn_signatures(source);
        let by_name: std::collections::HashMap<_, _> =
            sigs.into_iter().map(|s| (s.name.clone(), s)).collect();
        assert!(!by_name["clean"].is_unsafe);
        assert!(!by_name["also_clean"].is_unsafe);
        assert!(by_name["danger"].is_unsafe);
    }

    #[test]
    fn strip_pub_const_fn() {
        let (is_pub, is_unsafe, rest) = strip_fn_prefix("pub const fn SIZE()").unwrap();
        assert!(is_pub);
        assert!(!is_unsafe);
        assert_eq!(rest, "SIZE()");
    }

    #[test]
    fn strip_non_fn_line() {
        assert!(strip_fn_prefix("let x = 5;").is_none());
        assert!(strip_fn_prefix("struct Foo {}").is_none());
        assert!(strip_fn_prefix("// fn comment").is_none());
    }

    // ---- parse_param_list ----

    #[test]
    fn parse_empty_params() {
        let params = parse_param_list("");
        assert!(params.is_empty());
    }

    #[test]
    fn parse_single_param() {
        let params = parse_param_list("x: i64");
        assert_eq!(params.len(), 1);
        assert_eq!(params[0].0, "x");
        assert_eq!(params[0].1, "i64");
    }

    #[test]
    fn parse_multiple_params() {
        let params = parse_param_list("a: i32, b: &str, c: bool");
        assert_eq!(params.len(), 3);
        assert_eq!(params[0].0, "a");
        assert_eq!(params[1].0, "b");
        assert_eq!(params[2].0, "c");
    }

    #[test]
    fn parse_skips_self() {
        let params = parse_param_list("&self, x: i64");
        assert_eq!(params.len(), 1);
        assert_eq!(params[0].0, "x");
    }

    #[test]
    fn parse_generic_params() {
        let params = parse_param_list("items: Vec<String>, idx: usize");
        assert_eq!(params.len(), 2);
        assert_eq!(params[0].1, "Vec<String>");
        assert_eq!(params[1].0, "idx");
    }

    #[test]
    fn parse_nested_generic_params() {
        let params = parse_param_list("m: HashMap<String, Vec<i32>>");
        assert_eq!(params.len(), 1);
        assert_eq!(params[0].1, "HashMap<String, Vec<i32>>");
    }

    // ---- parse_fn_signature ----

    #[test]
    fn parse_simple_signature() {
        let sig = parse_fn_signature("add(a: i32, b: i32) -> i32 {", true, false).unwrap();
        assert_eq!(sig.name, "add");
        assert_eq!(sig.params.len(), 2);
        assert_eq!(sig.return_type, "i32");
        assert!(sig.is_pub);
        assert!(!sig.is_unsafe);
    }

    #[test]
    fn parse_no_return_type() {
        let sig = parse_fn_signature("init() {", false, false).unwrap();
        assert_eq!(sig.name, "init");
        assert_eq!(sig.return_type, "()");
    }

    #[test]
    fn parse_generic_fn() {
        let sig =
            parse_fn_signature("encode<T: Serialize>(value: T) -> String {", true, false).unwrap();
        assert_eq!(sig.name, "encode");
        assert_eq!(sig.params.len(), 1);
    }

    #[test]
    fn parse_where_clause_stripped() {
        let sig = parse_fn_signature(
            "process(data: Vec<u8>) -> Result<(), Error> where T: Clone {",
            true,
            false,
        )
        .unwrap();
        assert_eq!(sig.return_type, "Result<(), Error>");
    }

    // ---- extract_rust_fn_signatures ----

    #[test]
    fn extract_pub_fns_from_source() {
        let source = "pub fn add(a: i32, b: i32) -> i32 {\n    a + b\n}\n\nfn private_helper() {\n}\n\npub fn greet(name: &str) -> String {\n    format!(\"Hello, {name}\")\n}\n";
        let sigs = extract_rust_fn_signatures(source);
        assert_eq!(sigs.len(), 3);

        let pub_sigs: Vec<_> = sigs.iter().filter(|s| s.is_pub).collect();
        assert_eq!(pub_sigs.len(), 2);
        assert_eq!(pub_sigs[0].name, "add");
        assert_eq!(pub_sigs[1].name, "greet");
    }

    // ---- derive_rust_module_path ----

    #[test]
    fn module_path_no_src() {
        let path = derive_rust_module_path("foo/bar.rs");
        assert_eq!(path, "foo::bar");
    }

    // ---- analyze_body_text ----

    #[test]
    fn detects_division_pattern() {
        let suggs = analyze_body_text(
            "divide",
            "result = a / b",
            10,
            &["a".into(), "b".into()],
            &[],
        );
        assert!(suggs.iter().any(|s| s.pattern == "division"));
    }

    #[test]
    fn detects_unwrap_pattern() {
        let suggs = analyze_body_text("process", "x.unwrap()", 5, &[], &[]);
        assert!(suggs.iter().any(|s| s.pattern == "unwrap"));
    }

    #[test]
    fn detects_index_pattern() {
        let suggs = analyze_body_text(
            "lookup",
            "items[idx]",
            1,
            &["items".into(), "idx".into()],
            &[],
        );
        assert!(suggs.iter().any(|s| s.pattern == "index"));
    }

    #[test]
    fn detects_unsafe_pattern() {
        let suggs = analyze_body_text("raw_op", "unsafe { *ptr }", 1, &[], &[]);
        assert!(suggs.iter().any(|s| s.pattern == "unsafe"));
    }

    #[test]
    fn detects_panic_pattern() {
        let suggs = analyze_body_text("bail", "panic!(\"oh no\")", 1, &[], &[]);
        assert!(suggs.iter().any(|s| s.pattern == "panic"));
    }

    #[test]
    fn focus_filters_patterns() {
        let suggs = analyze_body_text(
            "mixed",
            "x.unwrap(); items[idx]; a / b",
            1,
            &["a".into(), "b".into(), "idx".into()],
            &["division"],
        );
        assert!(suggs.iter().all(|s| s.pattern == "division"));
    }

    #[test]
    fn no_false_positives_on_clean_body() {
        let suggs = analyze_body_text(
            "clean",
            "a + b * c",
            1,
            &["a".into(), "b".into(), "c".into()],
            &[],
        );
        assert!(suggs.is_empty());
    }

    // ---- generate_bind_skeleton ----

    #[test]
    fn bind_skeleton_has_input_and_output() {
        let sig = RustFnSig {
            name: "add".to_string(),
            params: vec![
                ("a".to_string(), "i64".to_string()),
                ("b".to_string(), "i64".to_string()),
            ],
            return_type: "i64".to_string(),
            is_pub: true,
            is_unsafe: false,
        };
        let mut out = String::new();
        generate_bind_skeleton("my_crate", &sig, &mut out);
        assert!(out.contains("bind \"my_crate::add\" as add"));
        assert!(out.contains("input(a: Int, b: Int)"));
        assert!(out.contains("output(result: Int)"));
    }

    #[test]
    fn bind_skeleton_unit_return_omits_output() {
        let sig = RustFnSig {
            name: "init".to_string(),
            params: vec![],
            return_type: "()".to_string(),
            is_pub: true,
            is_unsafe: false,
        };
        let mut out = String::new();
        generate_bind_skeleton("my_crate", &sig, &mut out);
        assert!(!out.contains("output"));
    }

    #[test]
    fn clean_public_fn_has_sig_for_minus_o_fallback() {
        // Heuristic suggestions are empty for pure arithmetic; -o must still
        // be able to extract public signatures for skeleton binds.
        let source = "pub fn add(a: i64, b: i64) -> i64 { a + b }\nfn private() {}\n";
        let sigs = extract_rust_fn_signatures(source);
        let public: Vec<_> = sigs.iter().filter(|s| s.is_pub).collect();
        assert_eq!(public.len(), 1);
        assert_eq!(public[0].name, "add");
        let mut out = String::new();
        generate_bind_skeleton("lib", public[0], &mut out);
        assert!(out.contains("bind \"lib::add\" as add"));
    }
}