///////////////////////////////////////////////////////////////////
//
// 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 is a set of key-value pairs, where each key is an
// identifier, and each value is either a number, a boolean, an XYZ coordinate,
// or a string.  A key-value pair can be either persistent or nonpersistent.
// So a typical animation step might be:
//
//    action=walk  [nonpersistent]
//    xyz=3,4,5    [persistent]
//    facing=320   [persistent]
//    plane=earth  [persistent]
//
// Persistent values are retained from one animation step to the next,
// nonpersistent values exist for one animation step only.
//
// Animation steps are stored encoded as strings, which is convenient for
// passing the data to unreal, but it means that the animation step has to be
// decoded whenever you want access to the key-value pairs.
//
// Each animation step has a hash value.  The hash value is generated
// by mixing the hash value of the previous step with the hash value
// of the encoded string of key-value pairs.
//
///////////////////////////////////////////////////////////////////

#ifndef ANIMQUEUE_HPP
#define ANIMQUEUE_HPP

#include "wrap-set.hpp"
#include "wrap-string.hpp"
#include "wrap-deque.hpp"
#include "wrap-unordered-map.hpp"

#include "luastack.hpp"
#include "streambuffer.hpp"
#include "debugcollector.hpp"
#include "util.hpp"

#include <cassert>
#include <ostream>

enum AnimValueType {
    T_STRING,
    T_NUMBER,
    T_BOOLEAN,
    T_XYZ,
    T_UNINITIALIZED
};

struct AnimValue {
    AnimValue() : persistent(false), type(T_UNINITIALIZED) {}
    
    bool persistent;
    AnimValueType type;
    eng::string str;
    util::DXYZ xyz;

    // These set the type, str, and xyz fields in a consistent way.
    void set_boolean(bool b);
    void set_number(double n);
    void set_xyz(const util::DXYZ &xyz);
    void set_string(std::string_view s);

    // The get the type, str, and xyz fields in a consistent way.
    bool get_boolean() const;
    double get_number() const;
    const util::DXYZ &get_xyz() const;
    std::string_view get_string() const;

    // Copy the value from another animvalue.  Don't copy the persistent flag.
    void copy_value(const AnimValue &other);
};


class AnimState
{
private:
    using Map = eng::map<eng::string, AnimValue>;
    Map map_;

    // Set the default value, internal
    //
    eng::string add_default(const eng::string &name, const AnimValue &v, const AnimState *other);

public:
    // Clear everything
    //
    void clear() { map_.clear(); }

    // Set the persistent flag on a single variable.
    // If the variable isn't present, add it.
    //
    void set_persistent(const eng::string &name);

    // Return if it contains a value for the specified name.
    //
    bool contains(const eng::string &name) { return map_.find(name) != map_.end(); }

    // Get the value of a specific variable.
    // If the variable isn't present, return a default value.
    //
    bool get_boolean(const eng::string &name);
    double get_number(const eng::string &name);
    util::DXYZ get_xyz(const eng::string &name);
    std::string_view get_string(const eng::string &name);
    
    // Set a single variable to a value of a specified type.
    // If the variable isn't present, add it.
    //
    void set_boolean(const eng::string &name, bool v);
    void set_number(const eng::string &name, double v);
    void set_xyz(const eng::string &name, const util::DXYZ &value);
    void set_string(const eng::string &name, std::string_view value);

    // Print a debug string into the stringstream.
    //
    void print_debug_string(eng::ostringstream &oss);
    
    // Return the debug string.
    eng::string debug_string();

    // Constructs an empty state.
    //
    AnimState() {}

    // Convert to an encoded string.
    //
    eng::string encode() const;

    // Decode an encoded string.
    //
    void decode(std::string_view enc);

    // Decode an encoded string, discarding non-persistent data.
    //
    void decode_persistent(std::string_view enc);

    // Add default values for all builtin persistent variables.
    //
    // For each builtin default (plane, xyz, facing, bp, model)
    //
    //  - Will generate an error if a value is already present,
    //    but the present value is of the wrong type.
    //
    //  - If 'other' is not nullptr, then we look in 'other' for a default
    //    value.  If a valid value of the correct type is present, it is
    //    used as the default value.
    //
    //  - If no default value can be found in 'other', then a hardwired
    //    default value is provided.
    //
    eng::string add_defaults(const AnimState *other);
    
    // Apply a configuration from a lua table.
    //
    // If a key already exists in the state, then type type from the table
    // must match the type from the existing state.
    //
    eng::string apply_lua(LuaCoreStack &LS0, LuaSlot tab, bool setpersist); 

    // Convert an animstate to a lua table.
    //
    // You can either convert the persistent key-value pairs, or the
    // nonpersistent.  So you'll need two lua tables to store both.
    //
    void to_lua(LuaCoreStack &LS, LuaSlot tab, bool persistent);

    // Parse a string, for unit testing.
    //
    void parse(std::string_view s);
    void clear_and_parse(std::string_view s);

    // Constructor from an encoded string.
    //
    AnimState(std::string_view s) { decode(s); }
};

struct AnimCoreState
{
    util::DXYZ xyz;
    eng::string plane;

    void decode(std::string_view enc);
};

class AnimQueue : public eng::nevernew {
private:
    struct Step {
        Step() { hash=0; }
        Step(const eng::string &e, uint64_t h) : encoding(e), hash(h) {}
        eng::string encoding;
        uint64_t hash;
    };

public:
    // Construct an empty animation queue.
    // clears the state to a valid state.
    //
    AnimQueue();

    // Size limit.
    //
    int32_t size_limit() const { return size_limit_; }

    // Clear and set the initial state.
    //
    void clear();
    void clear(const AnimState &initial);
    
    // Set the size limit.  Must be 2-250
    //
    void set_limit(int n);

    // Add an animation step.
    //
    // Note: add does not automatically compose the step with the previous
    // step, you have to do that yourself.
    //
    void add(const AnimState &state);

    // Serialize or deserialize to a StreamBuffer
    //
    void serialize(StreamBuffer *sb) const;
    void deserialize(StreamBuffer *sb);

    // Difference transmission
    //
    bool diff(const AnimQueue &auth, StreamBuffer *sb) const;
    void patch(StreamBuffer *sb, DebugCollector *dbc);

    // Check for exactly equal.  This does the full check of all
    // fields, it is used exclusively for debugging.
    //
    bool exactly_equal(const AnimQueue &aq) const;

    // Check for exactly equal (fast).  Compares the size, limit,
    // and hash of the last entry.  If these are equal, then the whole
    // thing should be equal.
    //
    bool exactly_equal_fast(const AnimQueue &aq) const;

    // Debug strings.
    //
    eng::string steps_debug_string() const;
    eng::string full_debug_string() const;

    // Get the final hash value.
    //
    uint64_t get_final_hash() const { return steps_.back().hash; }
    
    // Get the final entry, xyz and plane only.
    //
    AnimCoreState get_final_core_state() const;

    // Get the final entry, all persistent variables.
    //
    AnimState get_final_persistent() const;

    // Get the final entry, everything persistent and non-persistent.
    //
    AnimState get_final_everything() const;
    
private:
    int size_limit_;
    eng::deque<Step> steps_;
};

#endif // ANIMQUEUE_HPP