#pragma once
#include "Common.h"
#include "Python.h"
#include <libtcod.h>
#include <vector>
#include <cstdint>
#include <unordered_map>
#include <map>
#include <SFML/System/Vector2.hpp>

// Forward declarations
class PyBSP;
class PyBSPNode;
class PyBSPAdjacency;
class PyBSPAdjacentTiles;

// Adjacency cache - computed lazily, invalidated on generation change (#210)
struct BSPAdjacencyCache {
    std::vector<std::vector<int>> graph;              // graph[i] = neighbor indices for leaf i
    std::vector<TCOD_bsp_t*> leaf_pointers;           // leaf_pointers[i] = TCOD node for leaf i
    std::unordered_map<TCOD_bsp_t*, int> ptr_to_index; // Reverse lookup: node ptr -> index
    uint64_t generation;                               // Generation when computed
    // Wall tile cache: key=(self_index, neighbor_index) - perspective matters!
    // leaf0.adjacent_tiles[1] returns tiles on leaf0's edge, not symmetric with leaf1.adjacent_tiles[0]
    std::map<std::pair<int,int>, std::vector<sf::Vector2i>> wall_tiles_cache;
};

// Maximum recursion depth to prevent memory exhaustion
// 2^16 = 65536 potential leaf nodes, which is already excessive
constexpr int BSP_MAX_DEPTH = 16;

// Python object structure for BSP tree (root owner)
typedef struct {
    PyObject_HEAD
    TCOD_bsp_t* root;           // libtcod BSP root (owned, will be deleted)
    int orig_x, orig_y;         // Original bounds for clear()
    int orig_w, orig_h;
    uint64_t generation;        // Incremented on structural changes (clear, split)
    BSPAdjacencyCache* adjacency_cache;  // Lazy-computed adjacency graph (#210)
} PyBSPObject;

// Python object structure for BSPNode (lightweight reference)
typedef struct {
    PyObject_HEAD
    TCOD_bsp_t* node;           // libtcod BSP node (NOT owned)
    PyObject* bsp_owner;        // Reference to PyBSPObject to prevent dangling
    uint64_t generation;        // Generation at time of creation (for validity check)
} PyBSPNodeObject;

// BSP iterator for traverse()
typedef struct {
    PyObject_HEAD
    std::vector<TCOD_bsp_t*>* nodes;  // Pre-collected nodes
    size_t index;
    PyObject* bsp_owner;              // Reference to PyBSPObject
    uint64_t generation;              // Generation at iterator creation
} PyBSPIterObject;

// Python object for BSP.adjacency property (#210)
typedef struct {
    PyObject_HEAD
    PyObject* bsp_owner;        // Reference to PyBSPObject
    uint64_t generation;        // Generation at creation (for validity check)
} PyBSPAdjacencyObject;

// Python object for BSPNode.adjacent_tiles property (#210)
typedef struct {
    PyObject_HEAD
    PyObject* bsp_owner;        // Reference to PyBSPObject
    TCOD_bsp_t* node;           // The leaf node this belongs to
    int leaf_index;             // This leaf's index in adjacency graph
    uint64_t generation;        // Generation at creation (for validity check)
} PyBSPAdjacentTilesObject;

class PyBSP
{
public:
    // Python type interface
    static PyObject* pynew(PyTypeObject* type, PyObject* args, PyObject* kwds);
    static int init(PyBSPObject* self, PyObject* args, PyObject* kwds);
    static void dealloc(PyBSPObject* self);
    static PyObject* repr(PyObject* obj);

    // Properties
    static PyObject* get_bounds(PyBSPObject* self, void* closure);
    static PyObject* get_pos(PyBSPObject* self, void* closure);
    static PyObject* get_size(PyBSPObject* self, void* closure);
    static PyObject* get_root(PyBSPObject* self, void* closure);
    static PyObject* get_adjacency(PyBSPObject* self, void* closure);  // #210

    // Splitting methods (#202)
    static PyObject* split_once(PyBSPObject* self, PyObject* args, PyObject* kwds);
    static PyObject* split_recursive(PyBSPObject* self, PyObject* args, PyObject* kwds);
    static PyObject* clear(PyBSPObject* self, PyObject* Py_UNUSED(args));

    // Iteration methods (#204)
    static PyObject* leaves(PyBSPObject* self, PyObject* Py_UNUSED(args));
    static PyObject* traverse(PyBSPObject* self, PyObject* args, PyObject* kwds);

    // Query methods (#205)
    static PyObject* find(PyBSPObject* self, PyObject* args, PyObject* kwds);
    static PyObject* get_leaf(PyBSPObject* self, PyObject* args, PyObject* kwds);  // #210

    // HeightMap conversion (#206)
    static PyObject* to_heightmap(PyBSPObject* self, PyObject* args, PyObject* kwds);

    // Sequence protocol
    static Py_ssize_t len(PyBSPObject* self);
    static PyObject* iter(PyBSPObject* self);

    // Method and property definitions
    static PyMethodDef methods[];
    static PyGetSetDef getsetters[];
    static PySequenceMethods sequence_methods;
};

class PyBSPNode
{
public:
    // Python type interface
    static PyObject* pynew(PyTypeObject* type, PyObject* args, PyObject* kwds);
    static int init(PyBSPNodeObject* self, PyObject* args, PyObject* kwds);
    static void dealloc(PyBSPNodeObject* self);
    static PyObject* repr(PyObject* obj);

    // Comparison
    static PyObject* richcompare(PyObject* self, PyObject* other, int op);

    // Properties (#203)
    static PyObject* get_bounds(PyBSPNodeObject* self, void* closure);
    static PyObject* get_pos(PyBSPNodeObject* self, void* closure);
    static PyObject* get_size(PyBSPNodeObject* self, void* closure);
    static PyObject* get_level(PyBSPNodeObject* self, void* closure);
    static PyObject* get_is_leaf(PyBSPNodeObject* self, void* closure);
    static PyObject* get_split_horizontal(PyBSPNodeObject* self, void* closure);
    static PyObject* get_split_position(PyBSPNodeObject* self, void* closure);

    // Navigation properties (#203)
    static PyObject* get_left(PyBSPNodeObject* self, void* closure);
    static PyObject* get_right(PyBSPNodeObject* self, void* closure);
    static PyObject* get_parent(PyBSPNodeObject* self, void* closure);
    static PyObject* get_sibling(PyBSPNodeObject* self, void* closure);

    // Adjacency properties (#210)
    static PyObject* get_leaf_index(PyBSPNodeObject* self, void* closure);
    static PyObject* get_adjacent_tiles(PyBSPNodeObject* self, void* closure);

    // Methods (#203)
    static PyObject* contains(PyBSPNodeObject* self, PyObject* args, PyObject* kwds);
    static PyObject* center(PyBSPNodeObject* self, PyObject* Py_UNUSED(args));

    // Helper to create a BSPNode from a TCOD_bsp_t*
    static PyObject* create(TCOD_bsp_t* node, PyObject* bsp_owner);

    // Validity check - returns false and sets error if node is stale
    static bool checkValid(PyBSPNodeObject* self);

    // Method and property definitions
    static PyMethodDef methods[];
    static PyGetSetDef getsetters[];
};

// BSP Iterator class
class PyBSPIter
{
public:
    static void dealloc(PyBSPIterObject* self);
    static PyObject* iter(PyObject* self);
    static PyObject* next(PyBSPIterObject* self);
    static int init(PyBSPIterObject* self, PyObject* args, PyObject* kwds);
    static PyObject* repr(PyObject* obj);
};

// BSP Adjacency wrapper class (#210)
class PyBSPAdjacency
{
public:
    static void dealloc(PyBSPAdjacencyObject* self);
    static PyObject* repr(PyObject* obj);
    static Py_ssize_t len(PyBSPAdjacencyObject* self);
    static PyObject* getitem(PyBSPAdjacencyObject* self, Py_ssize_t index);
    static PyObject* subscript(PyBSPAdjacencyObject* self, PyObject* key);
    static PyObject* iter(PyBSPAdjacencyObject* self);
    static bool checkValid(PyBSPAdjacencyObject* self);

    static PySequenceMethods sequence_methods;
    static PyMappingMethods mapping_methods;
};

// BSP Adjacent Tiles wrapper class (#210)
class PyBSPAdjacentTiles
{
public:
    static void dealloc(PyBSPAdjacentTilesObject* self);
    static PyObject* repr(PyObject* obj);
    static Py_ssize_t len(PyBSPAdjacentTilesObject* self);
    static PyObject* subscript(PyBSPAdjacentTilesObject* self, PyObject* key);
    static int contains(PyBSPAdjacentTilesObject* self, PyObject* key);
    static PyObject* keys(PyBSPAdjacentTilesObject* self, PyObject* Py_UNUSED(args));
    static bool checkValid(PyBSPAdjacentTilesObject* self);

    static PyMappingMethods mapping_methods;
    static PySequenceMethods sequence_methods;  // For 'in' operator
    static PyMethodDef methods[];
};

// Traversal enum creation
class PyTraversal
{
public:
    static PyObject* traversal_enum_class;
    static PyObject* create_enum_class(PyObject* module);
    static int from_arg(PyObject* arg, int* out_order);
    // Cleanup for module finalization (optional)
    static void cleanup();
};

namespace mcrfpydef {
    // BSP - user-facing, exported
    inline PyTypeObject PyBSPType = {
        .ob_base = {.ob_base = {.ob_refcnt = 1, .ob_type = NULL}, .ob_size = 0},
        .tp_name = "mcrfpy.BSP",
        .tp_basicsize = sizeof(PyBSPObject),
        .tp_itemsize = 0,
        .tp_dealloc = (destructor)PyBSP::dealloc,
        .tp_repr = PyBSP::repr,
        .tp_as_sequence = &PyBSP::sequence_methods,
        .tp_flags = Py_TPFLAGS_DEFAULT,
        .tp_doc = PyDoc_STR(
            "BSP(pos: tuple[int, int], size: tuple[int, int])\n\n"
            "Binary Space Partitioning tree for procedural dungeon generation.\n\n"
            "BSP recursively divides a rectangular region into smaller sub-regions, "
            "creating a tree structure perfect for generating dungeon rooms and corridors.\n\n"
            "Args:\n"
            "    pos: (x, y) - Top-left position of the root region.\n"
            "    size: (w, h) - Width and height of the root region.\n\n"
            "Properties:\n"
            "    pos (tuple[int, int]): Read-only. Top-left position (x, y).\n"
            "    size (tuple[int, int]): Read-only. Dimensions (width, height).\n"
            "    bounds ((pos), (size)): Read-only. Combined position and size.\n"
            "    root (BSPNode): Read-only. Reference to the root node.\n\n"
            "Iteration:\n"
            "    for leaf in bsp:  # Iterates over leaf nodes (rooms)\n"
            "    len(bsp)          # Returns number of leaf nodes\n\n"
            "Example:\n"
            "    bsp = mcrfpy.BSP(pos=(0, 0), size=(80, 50))\n"
            "    bsp.split_recursive(depth=4, min_size=(8, 8))\n"
            "    for leaf in bsp:\n"
            "        print(f'Room at {leaf.pos}, size {leaf.size}')\n"
        ),
        .tp_iter = (getiterfunc)PyBSP::iter,
        .tp_methods = nullptr,  // Set in McRFPy_API.cpp
        .tp_getset = nullptr,   // Set in McRFPy_API.cpp
        .tp_init = (initproc)PyBSP::init,
        .tp_new = PyBSP::pynew,
    };

    // BSPNode - internal type (returned by BSP methods)
    inline PyTypeObject PyBSPNodeType = {
        .ob_base = {.ob_base = {.ob_refcnt = 1, .ob_type = NULL}, .ob_size = 0},
        .tp_name = "mcrfpy.BSPNode",
        .tp_basicsize = sizeof(PyBSPNodeObject),
        .tp_itemsize = 0,
        .tp_dealloc = (destructor)PyBSPNode::dealloc,
        .tp_repr = PyBSPNode::repr,
        .tp_flags = Py_TPFLAGS_DEFAULT,
        .tp_doc = PyDoc_STR(
            "BSPNode - Lightweight reference to a node in a BSP tree.\n\n"
            "BSPNode provides read-only access to node properties and navigation.\n"
            "Nodes are created by BSP methods, not directly instantiated.\n\n"
            "WARNING: BSPNode references become invalid after BSP.clear() or\n"
            "BSP.split_recursive(). Accessing properties of an invalid node\n"
            "raises RuntimeError.\n\n"
            "Properties:\n"
            "    pos (tuple[int, int]): Top-left position (x, y).\n"
            "    size (tuple[int, int]): Dimensions (width, height).\n"
            "    bounds ((pos), (size)): Combined position and size.\n"
            "    level (int): Depth in tree (0 for root).\n"
            "    is_leaf (bool): True if this node has no children.\n"
            "    split_horizontal (bool | None): Split orientation, None if leaf.\n"
            "    split_position (int | None): Split coordinate, None if leaf.\n"
            "    left (BSPNode | None): Left child, or None if leaf.\n"
            "    right (BSPNode | None): Right child, or None if leaf.\n"
            "    parent (BSPNode | None): Parent node, or None if root.\n"
            "    sibling (BSPNode | None): Other child of parent, or None.\n"
        ),
        .tp_richcompare = PyBSPNode::richcompare,
        .tp_methods = nullptr,  // Set in McRFPy_API.cpp
        .tp_getset = nullptr,   // Set in McRFPy_API.cpp
        .tp_init = (initproc)PyBSPNode::init,
        .tp_new = PyBSPNode::pynew,
    };

    // BSP Iterator - internal type
    inline PyTypeObject PyBSPIterType = {
        .ob_base = {.ob_base = {.ob_refcnt = 1, .ob_type = NULL}, .ob_size = 0},
        .tp_name = "mcrfpy.BSPIter",
        .tp_basicsize = sizeof(PyBSPIterObject),
        .tp_itemsize = 0,
        .tp_dealloc = (destructor)PyBSPIter::dealloc,
        .tp_repr = PyBSPIter::repr,
        .tp_flags = Py_TPFLAGS_DEFAULT,
        .tp_doc = PyDoc_STR("Iterator for BSP tree traversal."),
        .tp_iter = PyBSPIter::iter,
        .tp_iternext = (iternextfunc)PyBSPIter::next,
        .tp_init = (initproc)PyBSPIter::init,
        .tp_new = [](PyTypeObject* type, PyObject* args, PyObject* kwds) -> PyObject* {
            PyErr_SetString(PyExc_TypeError, "BSPIter cannot be instantiated directly");
            return NULL;
        },
    };

    // BSP Adjacency - internal type for BSP.adjacency property (#210)
    inline PyTypeObject PyBSPAdjacencyType = {
        .ob_base = {.ob_base = {.ob_refcnt = 1, .ob_type = NULL}, .ob_size = 0},
        .tp_name = "mcrfpy.BSPAdjacency",
        .tp_basicsize = sizeof(PyBSPAdjacencyObject),
        .tp_itemsize = 0,
        .tp_dealloc = (destructor)PyBSPAdjacency::dealloc,
        .tp_repr = PyBSPAdjacency::repr,
        .tp_as_sequence = &PyBSPAdjacency::sequence_methods,
        .tp_as_mapping = &PyBSPAdjacency::mapping_methods,
        .tp_flags = Py_TPFLAGS_DEFAULT,
        .tp_doc = PyDoc_STR(
            "BSPAdjacency - Sequence of leaf neighbor tuples.\n\n"
            "Accessed via BSP.adjacency property. adjacency[i] returns a tuple\n"
            "of leaf indices that are adjacent to (share a wall with) leaf i.\n"
        ),
        .tp_iter = (getiterfunc)PyBSPAdjacency::iter,
        .tp_new = [](PyTypeObject* type, PyObject* args, PyObject* kwds) -> PyObject* {
            PyErr_SetString(PyExc_TypeError, "BSPAdjacency cannot be instantiated directly");
            return NULL;
        },
    };

    // BSP Adjacent Tiles - internal type for BSPNode.adjacent_tiles property (#210)
    inline PyTypeObject PyBSPAdjacentTilesType = {
        .ob_base = {.ob_base = {.ob_refcnt = 1, .ob_type = NULL}, .ob_size = 0},
        .tp_name = "mcrfpy.BSPAdjacentTiles",
        .tp_basicsize = sizeof(PyBSPAdjacentTilesObject),
        .tp_itemsize = 0,
        .tp_dealloc = (destructor)PyBSPAdjacentTiles::dealloc,
        .tp_repr = PyBSPAdjacentTiles::repr,
        .tp_as_sequence = &PyBSPAdjacentTiles::sequence_methods,  // For 'in' operator
        .tp_as_mapping = &PyBSPAdjacentTiles::mapping_methods,
        .tp_flags = Py_TPFLAGS_DEFAULT,
        .tp_doc = PyDoc_STR(
            "BSPAdjacentTiles - Mapping of neighbor index to wall tile coordinates.\n\n"
            "Accessed via BSPNode.adjacent_tiles property. adjacent_tiles[j] returns\n"
            "a tuple of Vector coordinates representing tiles on THIS leaf's edge that\n"
            "border neighbor j. Each Vector has integer x/y coordinates (use .int for tuple).\n"
            "Raises KeyError if j is not an adjacent leaf.\n\n"
            "Supports 'in' operator: `5 in leaf.adjacent_tiles` checks if leaf 5 is adjacent.\n"
        ),
        .tp_methods = PyBSPAdjacentTiles::methods,
        .tp_new = [](PyTypeObject* type, PyObject* args, PyObject* kwds) -> PyObject* {
            PyErr_SetString(PyExc_TypeError, "BSPAdjacentTiles cannot be instantiated directly");
            return NULL;
        },
    };
}