///////////////////////////////////////////////////////////////////
//
// ANIMATION QUEUES
//
// An animation queue is a fifo queue of animation steps.  New animations are
// pushed on the back, and old ones are popped from the front.
//
// An animation step has an "action" which is usually the name of an animation,
// or it's a special token like "walk" or "warp." Each animation step shows the
// resulting AnimState that the player finds himself in after executing the
// action.
//
// The first step in an animation queue always has id=0 and action="". This step
// represents the initial state of the sprite before any animations or
// movements.
//
// To add new items to the AnimQueue, use this process: first, call add(id,
// action).  This adds a new step to the queue.  Then, call set_xyz, set_facing,
// set_plane, or an other setter. These setters are meant to only be used
// immediately after calling 'add' to populate the new step. 
//
///////////////////////////////////////////////////////////////////

#ifndef ANIMQUEUE_HPP
#define ANIMQUEUE_HPP

#include <set>
#include <string>
#include <deque>
#include <cassert>
#include <unordered_map>
#include "streambuffer.hpp"
#include "util.hpp"


class AnimStep {
    friend class AnimQueue;
public:
    enum {
        HAS_FACING = 1,
        HAS_X = 2,
        HAS_Y = 4,
        HAS_Z = 8,
        HAS_XYZ = 14,
        HAS_GRAPHIC = 16,
        HAS_PLANE = 32,
        HAS_EVERYTHING = 63,
    };     

private:
    int64_t id_;
    int16_t bits_;
    std::string action_;

    float facing_;
    util::XYZ xyz_;
    std::string graphic_;
    std::string plane_;

    void from_lua_store_string(lua_State *L, int idx, std::string *target, int16_t bits, const char *name);
    void from_lua_store_number(lua_State *L, int idx, float *target, float offset, int16_t bits, const char *name);
    
public:
    AnimStep();
    ~AnimStep();

    int64_t id() const { return id_; }
    int bits() const { return bits_; }

    const std::string &action() const { return action_; }
    double facing() const { return facing_; }
    float x() const { return xyz_.x; }
    float y() const { return xyz_.y; }
    float z() const { return xyz_.z; }
    const util::XYZ &xyz() const { return xyz_; }
    const std::string &graphic() const { return graphic_; }
    const std::string &plane() const { return plane_; }

    bool has_facing() const { return bits_ & HAS_FACING; }
    bool has_x() const { return bits_ & HAS_X; }
    bool has_y() const { return bits_ & HAS_Y; }
    bool has_z() const { return bits_ & HAS_Z; }
    bool has_xyz() const { return (bits_ & HAS_XYZ) == HAS_XYZ; }
    bool has_graphic() const { return bits_ & AnimStep::HAS_GRAPHIC; }
    bool has_plane() const { return bits_ & AnimStep::HAS_PLANE; }

    void set_action(const std::string &action);
    void set_facing(float f);
    void set_x(float f);
    void set_y(float f);
    void set_z(float z);
    void set_xyz(const util::XYZ &xyz);
    void set_graphic(const std::string &g);
    void set_plane(const std::string &p);

    void clear();

    // ExactlyEqual compares all fields.
    bool exactly_equal(const AnimStep &other) const;

    // LogicallyEqual only compares fields whose HAS_XXX bits are set.
    bool logically_equal(const AnimStep &other) const;

    // StateEqual is true if the plane, graphic, facing, and xyz match.
    bool state_equal(const AnimStep &other) const;

    // read/write the step using a stream buffer.
    //
    void write_into(StreamBuffer *sb) const;
    void read_from(StreamBuffer *sb);

    // Create an AnimStep from a lua table.
    //
    // Lua stack must contain a table, which may contain:
    //   action: "action"
    //   facing: 0.0 - 360.0
    //   x: x-coordinate
    //   y: y-coordinate
    //   z: z-coordinate
    //   graphic: "graphic"
    //   plane: "plane"
    //
    // qback: the animation queue back, from which relative
    // moves are computed.
    //
    void from_lua(lua_State *L, int idx, const AnimStep &qback);

    // Make this step into a first-step of an anim queue.
    void keep_state_only();
    
    // For any values that are unchanged in this step,
    // echo the values of the previous step.
    void echo(const AnimStep &prev);

    // Verify that this step echoes the previous step.
    bool echoes(const AnimStep &prev) const;
};

class AnimQueue {
private:
    int32_t size_limit_;
    std::deque<AnimStep> steps_;

public:    
    AnimQueue();
    
    bool exactly_equal(const AnimQueue &aq) const;

    const AnimStep &nth(int n) const { return steps_[n]; }
    size_t size() const { return steps_.size(); }
    int32_t size_limit() const { return size_limit_; }

    // Discard all but the most recent N steps.
    void keep_only(int n);

    // Clear the steps.
    // The resulting steps aren't empty.  There will be one
    // step in the queue, which will be on the plane "", at (0,0,0).
    // Doesn't affect size_limit.
    void clear_steps();
    
    // Mutator to create a new step.
    void add(int64_t id, const AnimStep &step);
    
    // Serialize or deserialize to a StreamBuffer
    void serialize(StreamBuffer *sb);
    void deserialize(StreamBuffer *sb);

    // Difference transmission
    //
    // When there are no differences, make_patch returns false but
    // still writes out a valid patch.
    //
    bool make_patch(const AnimQueue &auth, StreamBuffer *sb) const;
    void apply_patch(StreamBuffer *sb);

    // Get the final resting place after all animations are complete.
    const AnimStep &back() const;

    // (For testing): change the size limit.
    void set_size_limit(int32_t n);

    // (For testing): make sure the invariants are preserved.
    bool valid() const;
};

#endif // ANIMQUEUE_HPP