use crate::ast::compiler::bound_nodes::{BoundKind, Node};
use crate::ast::types::Value;
use crate::ast::vm::Closure;
use std::fmt::Debug;

/// Human-readable AST dumper for the bound AST.
pub struct Dumper {
    output: String,
    indent: usize,
}

impl Dumper {
    /// Produces a formatted string representation of the given bound AST node and its children.
    pub fn dump<T: Debug>(node: &Node<T>) -> String {
        let mut dumper = Self {
            output: String::new(),
            indent: 0,
        };
        dumper.visit(node);
        dumper.output
    }

    fn write_indent(&mut self) {
        for _ in 0..self.indent {
            self.output.push_str("  ");
        }
    }

    fn log<T: Debug>(&mut self, label: &str, node: &Node<T>) {
        self.write_indent();
        self.output.push_str(label);
        self.output
            .push_str(&format!(" <Metadata: {:?}>\n", node.ty));
    }

    fn visit<T: Debug>(&mut self, node: &Node<T>) {
        match &node.kind {
            BoundKind::Nop => self.log("Nop", node),
            BoundKind::Constant(v) => {
                self.log(&format!("Constant: {}", v), node);
                // Introspect Closure AST if possible
                if let Value::Object(obj) = v
                    && let Some(closure) = obj.as_any().downcast_ref::<Closure>()
                {
                    self.indent += 1;
                    self.write_indent();
                    self.output.push_str("--- Specialized Body ---\n");
                    // We need to cast the inner TypedNode to the generic T required by visit.
                    // Since Dumper is generic over T, but Closure stores TypedNode (where T = StaticType),
                    // we can only fully dump if T is StaticType.
                    // However, we can hack it by creating a new Dumper for the inner AST string.

                    // We can't call self.visit because types mismatch if T != StaticType.
                    // So we just recursively dump to string and append.
                    let inner_dump = Dumper::dump(&closure.function_node);
                    for line in inner_dump.lines() {
                        self.write_indent();
                        self.output.push_str(line);
                        self.output.push('\n');
                    }
                    self.indent -= 1;
                }
            }
            BoundKind::Get { addr, name } => {
                self.log(&format!("Get: {} ({:?})", name.name, addr), node)
            }

            BoundKind::FieldAccessor(k) => self.log(&format!("FieldAccessor: .{}", k.name()), node),

            BoundKind::GetField { rec, field } => {
                self.log(&format!("GetField: .{}", field.name()), node);
                self.indent += 1;
                self.visit(rec);
                self.indent -= 1;
            }

            BoundKind::Set { addr, value } => {
                self.log(&format!("Set: {:?}", addr), node);
                self.indent += 1;
                self.visit(value);
                self.indent -= 1;
            }

            BoundKind::Define {
                name,
                addr,
                kind,
                value,
                captured_by,
            } => {
                let k_str = match kind {
                    crate::ast::compiler::bound_nodes::DeclarationKind::Variable => "Variable",
                    crate::ast::compiler::bound_nodes::DeclarationKind::Parameter => "Parameter",
                };
                let capture_info = if captured_by.is_empty() {
                    String::from("not captured")
                } else {
                    format!("captured by {} lambdas", captured_by.len())
                };
                self.log(
                    &format!(
                        "Define {} (Name: '{}', Address: {:?}, {})",
                        k_str, name.name, addr, capture_info
                    ),
                    node,
                );

                self.indent += 1;
                if !captured_by.is_empty() {
                    for capturer in captured_by {
                        self.write_indent();
                        let loc = capturer
                            .location
                            .unwrap_or(crate::ast::types::SourceLocation { line: 0, col: 0 });
                        self.output.push_str(&format!(
                            "- Capturer: Lambda at line {}, col {}\n",
                            loc.line, loc.col
                        ));
                    }
                }
                self.visit(value);
                self.indent -= 1;
            }

            BoundKind::Destructure { pattern, value } => {
                self.log("Destructure", node);
                self.indent += 1;
                self.write_indent();
                self.output.push_str("Pattern:\n");
                self.visit(pattern);
                self.write_indent();
                self.output.push_str("Value:\n");
                self.visit(value);
                self.indent -= 1;
            }

            BoundKind::If {
                cond,
                then_br,
                else_br,
            } => {
                self.log("If", node);
                self.indent += 1;

                self.write_indent();
                self.output.push_str("Condition:\n");
                self.visit(cond);

                self.write_indent();
                self.output.push_str("Then:\n");
                self.visit(then_br);

                if let Some(e) = else_br {
                    self.write_indent();
                    self.output.push_str("Else:\n");
                    self.visit(e);
                }
                self.indent -= 1;
            }

            BoundKind::Lambda {
                params,
                upvalues,
                body,
                ..
            } => {
                self.log(&format!("Lambda (Upvalues: {})", upvalues.len()), node);
                self.indent += 1;

                self.write_indent();
                self.output.push_str("Parameters:\n");
                self.visit(params);

                if !upvalues.is_empty() {
                    self.write_indent();
                    self.output.push_str(&format!("Upvalues: {:?}\n", upvalues));
                }
                self.visit(body);
                self.indent -= 1;
            }

            BoundKind::Call { callee, args } => {
                self.log("Call", node);
                self.indent += 1;

                self.write_indent();
                self.output.push_str("Callee:\n");
                self.visit(callee);

                self.write_indent();
                self.output.push_str("Arguments:\n");
                self.visit(args);

                self.indent -= 1;
            }

            BoundKind::Again { args } => {
                self.log("Again", node);
                self.indent += 1;
                self.visit(args);
                self.indent -= 1;
            }
            BoundKind::Pipe { inputs, lambda, .. } => {
                self.log("Pipe", node);
                self.indent += 1;
                for input in inputs {
                    self.visit(input);
                }
                self.visit(lambda);
                self.indent -= 1;
            }

            BoundKind::Block { exprs } => {
                self.log("Block", node);
                self.indent += 1;
                for expr in exprs {
                    self.visit(expr);
                }
                self.indent -= 1;
            }

            BoundKind::Tuple { elements } => {
                self.log("Tuple", node);
                self.indent += 1;
                for el in elements {
                    self.visit(el);
                }
                self.indent -= 1;
            }

            BoundKind::Record { layout, values } => {
                self.log(
                    &format!("Record (Layout: {} fields)", layout.fields.len()),
                    node,
                );
                self.indent += 1;
                for v in values {
                    self.visit(v);
                }
                self.indent -= 1;
            }

            BoundKind::Expansion {
                original_call,
                bound_expanded,
            } => {
                self.log(
                    &format!("Expansion (Original: {:?})", original_call.kind),
                    node,
                );
                self.indent += 1;
                self.visit(bound_expanded);
                self.indent -= 1;
            }

            BoundKind::Extension(ext) => {
                self.log(&ext.display_name(), node);
            }
            BoundKind::Error => {
                self.log("ERROR_NODE", node);
            }
        }
    }
}