#include "viz/sparkline.h"
#include "imgui.h"

// Implementacion comun. Si auto_y=true, calcula min/max de values; si no,
// usa [y_min, y_max] explicitos.
static void sparkline_impl(const char* id, const float* values, int count,
                           ImVec4 color, float width, float height,
                           bool auto_y, float y_min, float y_max) {
    if (count <= 0) return;

    ImGui::PushID(id);

    ImVec2 pos = ImGui::GetCursorScreenPos();
    ImDrawList* draw_list = ImGui::GetWindowDrawList();

    ImGui::Dummy(ImVec2(width, height));

    if (auto_y) {
        y_min = values[0];
        y_max = values[0];
        for (int i = 1; i < count; i++) {
            if (values[i] < y_min) y_min = values[i];
            if (values[i] > y_max) y_max = values[i];
        }
    }
    float range = y_max - y_min;
    if (range < 1e-6f) range = 1.0f;

    auto y_at = [&](float v) {
        // Clamp visualmente al rango — para fixed Y sirve para que outliers
        // no salgan del card; para auto Y es no-op.
        if (v < y_min) v = y_min;
        if (v > y_max) v = y_max;
        return pos.y + height - ((v - y_min) / range) * height;
    };

    // Fade gradient v1.2: alpha sube de older->newer.
    // El segmento [i, i+1] se pinta con alpha proporcional al endpoint derecho
    // (mas cercano a "ahora"). Hace efecto de rastro / trail.
    const int r_ = (int)(color.x * 255);
    const int g_ = (int)(color.y * 255);
    const int b_ = (int)(color.z * 255);

    auto seg_t = [&](int i) {
        return (count > 1) ? (float)(i + 1) / (float)(count - 1) : 1.0f;
    };

    if (count >= 2) {
        float x0 = pos.x;
        float y_base = pos.y + height;
        for (int i = 0; i + 1 < count; i++) {
            float t = seg_t(i);
            int fill_a = (int)((0.10f + 0.70f * t) * 40.0f); // 4..28 alpha
            ImU32 fill_color = IM_COL32(r_, g_, b_, fill_a);
            float xa = x0 + ((float)i       / (count - 1)) * width;
            float xb = x0 + ((float)(i + 1) / (count - 1)) * width;
            float ya = y_at(values[i]);
            float yb = y_at(values[i + 1]);
            draw_list->AddQuadFilled(
                ImVec2(xa, y_base), ImVec2(xa, ya),
                ImVec2(xb, yb),     ImVec2(xb, y_base),
                fill_color);
        }
    }

    for (int i = 0; i + 1 < count; i++) {
        float t = seg_t(i);
        float a = 0.20f + 0.80f * t;
        ImU32 line_color = IM_COL32(r_, g_, b_, (int)(color.w * a * 255));
        float xa = pos.x + ((float)i       / (count - 1)) * width;
        float xb = pos.x + ((float)(i + 1) / (count - 1)) * width;
        float ya = y_at(values[i]);
        float yb = y_at(values[i + 1]);
        draw_list->AddLine(ImVec2(xa, ya), ImVec2(xb, yb), line_color, 1.5f);
    }

    ImGui::PopID();
}

void sparkline(const char* id, const float* values, int count, ImVec4 color,
               float width, float height) {
    sparkline_impl(id, values, count, color, width, height,
                   /*auto_y=*/true, 0.0f, 0.0f);
}

void sparkline(const char* id, const float* values, int count,
               float width, float height) {
    sparkline(id, values, count, ImVec4(0.35f, 0.85f, 0.45f, 1.0f), width, height);
}

void sparkline(const char* id, const float* values, int count, ImVec4 color,
               float y_min, float y_max, float width, float height) {
    sparkline_impl(id, values, count, color, width, height,
                   /*auto_y=*/false, y_min, y_max);
}

void sparkline(const char* id, const float* values, int count,
               float y_min, float y_max, float width, float height) {
    sparkline(id, values, count, ImVec4(0.35f, 0.85f, 0.45f, 1.0f),
              y_min, y_max, width, height);
}