#pragma once
// Player movement, run identically by the server (authoritative) and the
// client (prediction + reconciliation). Pure function of state + input.

#include "Protocol.h"
#include "Zone.h"

namespace bs {

constexpr float kWalkSpeed = 4.0f;  // world units / second
constexpr float kRunSpeed = 6.6f;

struct MoveState {
    glm::vec2 pos{0.0f};
    float yaw = 0.0f;
    bool moving = false;
    bool running = false;
};

inline void stepMovement(const Zone& zone, MoveState& s, const InputCmd& in, float dt) {
    glm::vec2 dir = in.move();
    float amount = std::min(glm::length(dir), 1.0f);
    s.moving = amount > 0.05f;
    s.running = s.moving && in.run();
    if (!s.moving) return;
    dir = glm::normalize(dir) * amount;
    s.yaw = yawFromDir(dir);
    glm::vec2 step = dir * (s.running ? kRunSpeed : kWalkSpeed) * dt;
    // Axis-separated resolution slides along obstacles.
    glm::vec2 p = s.pos;
    if (zone.walkable(p, p + glm::vec2(step.x, 0.0f))) p.x += step.x;
    if (zone.walkable(p, p + glm::vec2(0.0f, step.y))) p.y += step.y;
    s.pos = p;
}

// Quantizes a world direction exactly like the network does, so prediction
// uses the same input the server will see.
inline InputCmd makeInput(uint32_t seq, glm::vec2 worldDir, bool run) {
    InputCmd c;
    c.seq = seq;
    float len = glm::length(worldDir);
    if (len > 1.0f) worldDir /= len;
    c.moveX = int8_t(std::lround(glm::clamp(worldDir.x, -1.0f, 1.0f) * 127.0f));
    c.moveZ = int8_t(std::lround(glm::clamp(worldDir.y, -1.0f, 1.0f) * 127.0f));
    c.flags = run ? 1 : 0;
    return c;
}

}  // namespace bs