#include "draw.h"
#include "renderer.h"
#include "math.h"
#include "font.h"
#include "scratch.h"
#include "sprite.h"
#include "collider.h"

GLOBAL struct {
    struct renderer_texture solid_white;
} G = ZI, DEBUG_ALIAS(G, G_draw);

/* ========================== *
 * Startup
 * ========================== */

struct draw_startup_receipt draw_startup(struct renderer_startup_receipt *renderer_sr,
                                         struct font_startup_receipt *font_sr)
{
    (UNUSED)renderer_sr;
    (UNUSED)font_sr;
    u32 pixel_white = 0xFFFFFFFF;
    G.solid_white = renderer_texture_alloc(RENDERER_TEXTURE_FORMAT_R8G8B8A8_UNORM, 0, V2I32(1, 1), &pixel_white);
    return (struct draw_startup_receipt) { 0 };
}

/* ========================== *
 * Texture
 * ========================== */

void draw_quad_texture_ex(struct renderer_cmd_buffer *cmdbuff, struct renderer_texture texture, struct sprite_tag sprite, struct clip_rect clip, u32 tint0, u32 tint1, struct quad quad)
{
    struct renderer_cmd_parameters cmd_params = ZI;
    cmd_params.kind = SHADER_TRIANGLE;
    cmd_params.texture_params.texture = texture;
    cmd_params.texture_params.sprite = sprite;
    renderer_cmd_buffer_ensure_cmd(cmdbuff, &cmd_params);

    struct triangle_shader_vertex *vertices = NULL;
    vidx *indices = NULL;
    u32 offset = renderer_cmd_buffer_push_vertices(cmdbuff, (u8 **)&vertices, &indices, 4, 6);

    /* Top left */
    vertices[0] = (struct triangle_shader_vertex) {
        .pos = quad.p0,
        .uv = { clip.p0.x, clip.p0.y },
        .color = tint0
    };
    /* Top right */
    vertices[1] = (struct triangle_shader_vertex) {
        .pos = quad.p1,
        .uv = { clip.p1.x, clip.p0.y },
        .color = tint0
    };
    /* Bottom right */
    vertices[2] = (struct triangle_shader_vertex) {
        .pos = quad.p2,
        .uv = { clip.p1.x, clip.p1.y },
        .color = tint1
    };
    /* Bottom left */
    vertices[3] = (struct triangle_shader_vertex) {
        .pos = quad.p3,
        .uv = { clip.p0.x, clip.p1.y },
        .color = tint1
    };

    /* Top / right triangle */
    indices[0] = offset + 0;
    indices[1] = offset + 1;
    indices[2] = offset + 2;

    /* Bottom / left triangle */
    indices[3] = offset + 0;
    indices[4] = offset + 2;
    indices[5] = offset + 3;
}

void draw_quad_texture(struct renderer_cmd_buffer *cmdbuff, struct draw_texture_params params, struct quad quad)
{
    draw_quad_texture_ex(cmdbuff, params.texture, params.sprite, params.clip, params.tint, params.tint, quad);
}

/* ========================== *
 * Solid fill shapes
 * ========================== */

void draw_poly(struct renderer_cmd_buffer *cmdbuff, struct v2_array array, u32 color)
{
    if (array.count < 3) {
        return;
    }

    struct renderer_cmd_parameters cmd_params = ZI;
    cmd_params.kind = SHADER_TRIANGLE;
    cmd_params.texture_params.texture = G.solid_white;
    renderer_cmd_buffer_ensure_cmd(cmdbuff, &cmd_params);

    u32 num_tris = array.count - 2;
    u32 num_indices = num_tris * 3;

    struct triangle_shader_vertex *vertices = NULL;
    vidx *indices = NULL;
    u32 idx_offset = renderer_cmd_buffer_push_vertices(cmdbuff, (u8 **)&vertices, &indices, array.count, num_indices);

    /* Fill vertices */
    for (u32 i = 0; i < array.count; ++i) {
        vertices[i] = (struct triangle_shader_vertex) {
            .pos = array.points[i],
            .color = color
        };
    }

    /* Fill indices */
    for (u32 i = 0; i < num_tris; ++i) {
        u32 tri_offset = i * 3;
        indices[tri_offset + 0] = idx_offset + 0;
        indices[tri_offset + 1] = idx_offset + (i + 1);
        indices[tri_offset + 2] = idx_offset + (i + 2);
    }
}

void draw_circle(struct renderer_cmd_buffer *cmdbuff, struct v2 pos, f32 radius, u32 color, u32 detail)
{
    struct temp_arena scratch = scratch_begin_no_conflict();

    struct v2 *points = arena_push_array_no_zero(scratch.arena, struct v2, detail);
    for(u32 i = 0; i < detail; ++i) {
        struct v2 p = V2(
            radius * math_cos(i * (PI * 2.f) / detail),
            radius * math_sin(i * (PI * 2.f) / detail)
        );
        points[i] = v2_add(pos, p);
    }

    struct v2_array a = {
        .points = points,
        .count = detail
    };
    draw_poly(cmdbuff, a, color);

    scratch_end(scratch);
}

void draw_quad(struct renderer_cmd_buffer *cmdbuff, struct quad quad, u32 color)
{
    draw_quad_texture_ex(cmdbuff, G.solid_white, sprite_tag_nil(), CLIP_ALL, color, color, quad);
}

/* ========================== *
 * Solid line shapes
 * ========================== */

void draw_gradient_line(struct renderer_cmd_buffer *cmdbuff, struct v2 start, struct v2 end, f32 thickness, u32 color_start, u32 color_end)
{
    struct quad quad = quad_from_line(start, end, thickness);
    draw_quad_texture_ex(cmdbuff, G.solid_white, sprite_tag_nil(), CLIP_ALL, color_start, color_end, quad);
}

void draw_line(struct renderer_cmd_buffer *cmdbuff, struct v2 start, struct v2 end, f32 thickness, u32 color)
{
    struct quad quad = quad_from_line(start, end, thickness);
    draw_quad(cmdbuff, quad, color);
}

void draw_ray(struct renderer_cmd_buffer *cmdbuff, struct v2 pos, struct v2 rel, f32 thickness, u32 color)
{
    struct quad quad = quad_from_ray(pos, rel, thickness);
    draw_quad(cmdbuff, quad, color);
}

void draw_poly_line(struct renderer_cmd_buffer *cmdbuff, struct v2_array array, b32 loop, f32 thickness, u32 color)
{
    if (array.count < 2) {
        return;
    }

    for (u64 i = 1; i < array.count; ++i) {
        struct v2 p1 = array.points[i - 1];
        struct v2 p2 = array.points[i];
        struct quad q = quad_from_line(p1, p2, thickness);
        draw_quad(cmdbuff, q, color);
    }
    if (loop && array.count > 2) {
        struct v2 p1 = array.points[array.count - 1];
        struct v2 p2 = array.points[0];
        struct quad q = quad_from_line(p1, p2, thickness);
        draw_quad(cmdbuff, q, color);
    }
}

void draw_circle_line(struct renderer_cmd_buffer *cmdbuff, struct v2 pos, f32 radius, f32 thickness, u32 color, u32 detail)
{
    struct temp_arena scratch = scratch_begin_no_conflict();

    struct v2 *points = arena_push_array_no_zero(scratch.arena, struct v2, detail);
    for (u32 i = 0; i < detail; ++i) {
        struct v2 p = V2(
            radius * math_cos(i * (PI * 2.f) / detail),
            radius * math_sin(i * (PI * 2.f) / detail)
        );
        points[i] = v2_add(pos, p);
    }

    struct v2_array a = {
        .points = points,
        .count = detail
    };
    draw_poly_line(cmdbuff, a, true, thickness, color);

    scratch_end(scratch);
}

void draw_quad_line(struct renderer_cmd_buffer *cmdbuff, struct quad quad, f32 thickness, u32 color)
{
    struct v2 points[] = { quad.p0, quad.p1, quad.p2, quad.p3 };
    struct v2_array a = { .points = points, .count = ARRAY_COUNT(points) };
    draw_poly_line(cmdbuff, a, true, thickness, color);
}

void draw_arrow_line(struct renderer_cmd_buffer *cmdbuff, struct v2 start, struct v2 end, f32 thickness, f32 arrowhead_height, u32 color)
{
    const f32 head_width_ratio = 0.5f;  /* Width of arrowhead relative to its length */

    const f32 max_height_to_line_ratio = 0.9f;  /* Maximum length of arrowhead relative to total line length */
    arrowhead_height = min_f32(arrowhead_height, v2_len(v2_sub(end, start)) * max_height_to_line_ratio);

    struct v2 head_start_dir = v2_sub(start, end);
    head_start_dir = v2_norm(head_start_dir);
    head_start_dir = v2_mul(head_start_dir, arrowhead_height);

    struct v2 head_start = v2_add(end, head_start_dir);

    struct v2 head_p1_dir = v2_perp_mul(head_start_dir, head_width_ratio);
    struct v2 head_p2_dir = v2_neg(head_p1_dir);

    struct v2 head_p1 = v2_add(head_start, head_p1_dir);
    struct v2 head_p2 = v2_add(head_start, head_p2_dir);

    struct v2 head_points[] = { end, head_p1, head_p2 };
    struct v2_array head_points_v2_array = {
        .points = head_points,
        .count = ARRAY_COUNT(head_points)
    };
    draw_poly(cmdbuff, head_points_v2_array, color);

    struct quad line_quad = quad_from_line(start, head_start, thickness);
    draw_quad(cmdbuff, line_quad, color);
}

void draw_arrow_ray(struct renderer_cmd_buffer *cmdbuff, struct v2 pos, struct v2 rel, f32 thickness, f32 arrowhead_height, u32 color)
{
    struct v2 end = v2_add(pos, rel);
    draw_arrow_line(cmdbuff, pos, end, thickness, arrowhead_height, color);
}

void draw_collider_line(struct renderer_cmd_buffer *cmdbuff, struct xform draw_xf, struct collider_shape shape, struct xform shape_xf, f32 thickness, u32 color, u32 detail)
{
    struct temp_arena scratch = scratch_begin_no_conflict();

    struct v2 *points = arena_push_array_no_zero(scratch.arena, struct v2, detail);
    for (u32 i = 0; i < detail; ++i) {
        f32 angle = ((f32)i / (f32)detail) * (2 * PI);
        struct v2 dir = V2(math_cos(angle), math_sin(angle));
        struct v2 p = collider_get_support_point(&shape, shape_xf, dir).p;
        p = xform_mul_v2(draw_xf, p);
        points[i] = p;
    }

#if 1
    struct v2_array poly = { .points = points, .count = detail };
    draw_poly_line(cmdbuff, poly, true, thickness, color);
#else
    for (u64 i = 0; i < detail; ++i) {
        struct v2 point = points[i];
        (UNUSED)thickness;
        draw_circle(cmdbuff, point, 3, color, 10);
    }
#endif

    scratch_end(scratch);
}

/* ========================== *
 * Grid
 * ========================== */

void draw_grid(struct renderer_cmd_buffer *cmdbuff, struct rect rect, u32 color, f32 thickness, f32 spacing, struct v2 offset)
{
    struct renderer_cmd_parameters cmd_params = ZI;
    cmd_params.kind = SHADER_GRID;
    renderer_cmd_buffer_ensure_cmd(cmdbuff, &cmd_params);

    struct grid_shader_vertex *vertices = NULL;
    vidx *indices = NULL;
    u32 index_offset = renderer_cmd_buffer_push_vertices(cmdbuff, (u8 **)&vertices, &indices, 4, 6);

    struct quad quad = quad_from_rect(rect);

    struct grid_shader_vertex attributes = ZI;
    attributes.color = color;
    attributes.line_thickness = thickness;
    attributes.line_spacing = spacing;
    attributes.offset = offset;

    /* Top left */
    vertices[0] = attributes;
    vertices[0].pos = quad.p0;
    /* Top right */
    vertices[1] = attributes;
    vertices[1].pos = quad.p1;
    /* Bottom right */
    vertices[2] = attributes;
    vertices[2].pos = quad.p2;
    /* Bottom left */
    vertices[3] = attributes;
    vertices[3].pos = quad.p3;

    /* Top / right triangle */
    indices[0] = index_offset + 0;
    indices[1] = index_offset + 1;
    indices[2] = index_offset + 2;
    /* Bottom / left triangle */
    indices[3] = index_offset + 0;
    indices[4] = index_offset + 2;
    indices[5] = index_offset + 3;
}

/* ========================== *
 * Text
 * ========================== */

void draw_text_ex(struct renderer_cmd_buffer *cmdbuff, struct font *font, struct v2 pos, f32 scale, struct string str)
{
    struct v2 draw_pos = pos;
    draw_pos.y += font->point_size * scale;

    struct string_codepoint_iter iter = string_codepoint_iter_begin(str);
    while (string_codepoint_iter_next(&iter)) {
        u32 codepoint = iter.codepoint;

        /* TODO: Remove this (placeholder \n) */
        if (codepoint == '\n') {
            draw_pos.x = pos.x;
            draw_pos.y += (font->point_size * 1.5f) * scale;
            continue;
        }

        struct font_glyph *glyph = font_get_glyph(font, codepoint);
        f32 x = draw_pos.x + glyph->off_x * scale;
        f32 y = draw_pos.y + glyph->off_y * scale;
        f32 width = glyph->width * scale;
        f32 height = glyph->height * scale;

        struct clip_rect clip = {
            {
                glyph->atlas_rect.x / (f32)font->image_width,
                glyph->atlas_rect.y / (f32)font->image_height
            },

            {
                (glyph->atlas_rect.x + glyph->atlas_rect.width) / (f32)font->image_width,
                (glyph->atlas_rect.y + glyph->atlas_rect.height) / (f32)font->image_height
            }
        };

        struct quad quad = quad_from_rect(RECT(x, y, width, height));
        draw_quad_texture_ex(cmdbuff, font->texture, sprite_tag_nil(), clip, COLOR_WHITE, COLOR_WHITE, quad);

        draw_pos.x += glyph->advance * scale;
    }
    string_codepoint_iter_end(&iter);
}

void draw_text(struct renderer_cmd_buffer *cmdbuff, struct font *font, struct v2 pos, struct string str)
{
    draw_text_ex(cmdbuff, font, pos, 1.0, str);
}