use tree_sitter::Node;

use archlens_domain::{CodeElement, CodeElementKind, Relationship, RelationshipKind};

use crate::extraction_context::ExtractionContext;
use crate::language_extractor::LanguageExtractor;

pub struct PythonExtractor;

impl LanguageExtractor for PythonExtractor {
    fn tree_sitter_language(&self) -> tree_sitter::Language {
        tree_sitter_python::LANGUAGE.into()
    }

    fn extract_types(&self, root: &Node, source: &str, ctx: &mut ExtractionContext) {
        // collect_classes handles class elements, inheritance, and field compositions
        // in a single pass — Python's relationship extraction is interleaved with type extraction
        collect_classes(root, source, ctx);
    }

    fn extract_relationships(&self, _root: &Node, _source: &str, _ctx: &mut ExtractionContext) {
        // Relationships are collected inside collect_classes for Python
    }

    fn extract_imports(&self, root: &Node, source: &str, ctx: &mut ExtractionContext) {
        collect_imports(root, source, ctx);
    }
}

fn collect_classes(node: &Node, source: &str, ctx: &mut ExtractionContext) {
    let mut cursor = node.walk();
    for child in node.children(&mut cursor) {
        if child.kind() != "class_definition" {
            continue;
        }

        let Some(name_node) = child.child_by_field_name("name") else {
            continue;
        };

        let name = &source[name_node.byte_range()];
        let line = child.start_position().row + 1;

        let methods = child
            .child_by_field_name("body")
            .map(|body| collect_methods(&body, source))
            .unwrap_or_default();

        match CodeElement::new(name, CodeElementKind::Class, ctx.file_path().clone(), line) {
            Ok(element) => ctx.add_element(element.with_methods(methods)),
            Err(e) => {
                ctx.add_warning(ctx.file_path().clone(), line, &e.to_string());
                continue;
            }
        }

        if let Some(superclasses) = child.child_by_field_name("superclasses") {
            collect_inheritance(&superclasses, source, name, ctx);
        }

        if let Some(body) = child.child_by_field_name("body") {
            collect_typed_fields(&body, source, name, ctx);
            collect_constructor_params(&body, source, name, ctx);
        }
    }
}

fn collect_inheritance(
    superclasses: &Node,
    source: &str,
    class_name: &str,
    ctx: &mut ExtractionContext,
) {
    let mut cursor = superclasses.walk();
    for child in superclasses.children(&mut cursor) {
        if child.kind() == "identifier" {
            let base_name = &source[child.byte_range()];
            if !is_python_builtin(base_name)
                && let Ok(rel) =
                    Relationship::new(class_name, base_name, RelationshipKind::Inheritance)
            {
                ctx.add_relationship(rel);
            }
        }
    }
}

const PYTHON_BUILTINS: &[&str] = &[
    "str",
    "int",
    "float",
    "bool",
    "bytes",
    "list",
    "dict",
    "set",
    "tuple",
    "None",
    "type",
    "object",
    "Exception",
    "BaseException",
    "Optional",
    "Any",
    "Union",
    "List",
    "Dict",
    "Set",
    "Tuple",
    "Callable",
    "Sequence",
    "Mapping",
    "Iterable",
    "Iterator",
    "Generator",
    "Coroutine",
    "AsyncGenerator",
    "ClassVar",
    "Final",
    "Literal",
    "TypeVar",
    "Generic",
    "Protocol",
    "runtime_checkable",
    "Self",
];

fn is_python_builtin(name: &str) -> bool {
    PYTHON_BUILTINS.contains(&name)
}

const STDLIB_MODULES: &[&str] = &[
    "os",
    "sys",
    "typing",
    "logging",
    "json",
    "re",
    "io",
    "abc",
    "collections",
    "datetime",
    "enum",
    "functools",
    "hashlib",
    "http",
    "importlib",
    "inspect",
    "itertools",
    "math",
    "pathlib",
    "pickle",
    "random",
    "shutil",
    "signal",
    "socket",
    "string",
    "subprocess",
    "tempfile",
    "threading",
    "time",
    "traceback",
    "unittest",
    "urllib",
    "uuid",
    "warnings",
    "contextlib",
    "dataclasses",
    "copy",
    "struct",
    "base64",
    "csv",
    "glob",
    "operator",
    "textwrap",
    "asyncio",
    "concurrent",
    "multiprocessing",
];

fn is_external_import(module: &str) -> bool {
    let top = module.split('.').next().unwrap_or(module);
    if STDLIB_MODULES.contains(&top) {
        return true;
    }
    if top.starts_with('_') {
        return true;
    }
    false
}

fn collect_imports(node: &Node, source: &str, ctx: &mut ExtractionContext) {
    let file_name = std::path::Path::new(ctx.file_path().as_str())
        .file_stem()
        .and_then(|s| s.to_str())
        .unwrap_or("unknown")
        .to_string();

    let mut cursor = node.walk();
    for child in node.children(&mut cursor) {
        match child.kind() {
            "import_statement" => {
                let mut name_cursor = child.walk();
                for name_child in child.children(&mut name_cursor) {
                    if name_child.kind() == "dotted_name" {
                        let module = &source[name_child.byte_range()];
                        if !is_external_import(module)
                            && let Ok(rel) =
                                Relationship::new(&file_name, module, RelationshipKind::Import)
                        {
                            ctx.add_relationship(rel);
                        }
                    }
                }
            }
            "import_from_statement" => {
                if let Some(module_node) = child.child_by_field_name("module_name") {
                    let module = &source[module_node.byte_range()];
                    if !is_external_import(module)
                        && let Ok(rel) =
                            Relationship::new(&file_name, module, RelationshipKind::Import)
                    {
                        ctx.add_relationship(rel);
                    }
                }
            }
            _ => {}
        }
    }
}

fn collect_methods(body: &Node, source: &str) -> Vec<String> {
    let mut methods = Vec::new();
    let mut cursor = body.walk();
    for child in body.children(&mut cursor) {
        if child.kind() != "function_definition" {
            continue;
        }
        let Some(name_node) = child.child_by_field_name("name") else {
            continue;
        };
        let fn_name = &source[name_node.byte_range()];
        if fn_name.starts_with('_') {
            continue;
        }

        let params = child
            .child_by_field_name("parameters")
            .map(|p| extract_python_params(&p, source))
            .unwrap_or_default();

        let ret = child
            .child_by_field_name("return_type")
            .map(|n| source[n.byte_range()].trim().to_string())
            .unwrap_or_default();

        let sig = if ret.is_empty() {
            format!("+{fn_name}({params})")
        } else {
            format!("+{fn_name}({params}) -> {ret}")
        };
        methods.push(sig);
    }
    methods
}

fn extract_python_params(params_node: &Node, source: &str) -> String {
    let mut parts = Vec::new();
    let mut cursor = params_node.walk();
    for param in params_node.children(&mut cursor) {
        match param.kind() {
            "typed_parameter" => {
                if let Some(type_node) = param.child_by_field_name("type") {
                    let mut inner = param.walk();
                    let name = param
                        .children(&mut inner)
                        .find(|c| c.kind() == "identifier")
                        .map(|c| &source[c.byte_range()])
                        .unwrap_or_default();
                    if name != "self" && name != "cls" && !name.is_empty() {
                        let ty = source[type_node.byte_range()].trim();
                        parts.push(format!("{name}: {ty}"));
                    }
                }
            }
            "identifier" => {
                let name = &source[param.byte_range()];
                if name != "self" && name != "cls" {
                    parts.push(name.to_string());
                }
            }
            _ => {}
        }
    }
    parts.join(", ")
}

fn collect_constructor_params(
    body: &Node,
    source: &str,
    class_name: &str,
    ctx: &mut ExtractionContext,
) {
    let mut cursor = body.walk();
    for child in body.children(&mut cursor) {
        if child.kind() != "function_definition" {
            continue;
        }
        let Some(fn_name) = child.child_by_field_name("name") else {
            continue;
        };
        if &source[fn_name.byte_range()] != "__init__" {
            continue;
        }
        let Some(params) = child.child_by_field_name("parameters") else {
            continue;
        };
        let mut param_cursor = params.walk();
        for param in params.children(&mut param_cursor) {
            if param.kind() == "typed_parameter"
                && let Some(type_node) = param.child_by_field_name("type")
            {
                let type_text = &source[type_node.byte_range()];
                let base_type = type_text.split('[').next().unwrap_or(type_text).trim();
                if base_type != class_name
                    && !base_type.is_empty()
                    && !is_python_builtin(base_type)
                    && let Ok(rel) =
                        Relationship::new(class_name, base_type, RelationshipKind::Composition)
                {
                    ctx.add_relationship(rel);
                }
            }
        }
    }
}

fn collect_typed_fields(body: &Node, source: &str, class_name: &str, ctx: &mut ExtractionContext) {
    collect_typed_fields_recursive(body, source, class_name, ctx);
}

fn collect_typed_fields_recursive(
    node: &Node,
    source: &str,
    class_name: &str,
    ctx: &mut ExtractionContext,
) {
    let mut cursor = node.walk();
    for child in node.children(&mut cursor) {
        if (child.kind() == "assignment" || child.kind() == "typed_assignment")
            && let Some(type_node) = child.child_by_field_name("type")
        {
            let type_text = &source[type_node.byte_range()];
            let base_type = type_text.split('[').next().unwrap_or(type_text).trim();
            if base_type != class_name
                && !base_type.is_empty()
                && !is_python_builtin(base_type)
                && let Ok(rel) =
                    Relationship::new(class_name, base_type, RelationshipKind::Composition)
            {
                ctx.add_relationship(rel);
            }
        }

        collect_typed_fields_recursive(&child, source, class_name, ctx);
    }
}