local M = {}

local COLOR_BACKDROP = 0x000000C0
local COLOR_BG       = 0x303030FF
local COLOR_BTN      = 0x404040FF
local COLOR_BTN_HOT  = 0x606060FF
local COLOR_TEXT     = 0xE0E0E0FF
local FONT_TITLE     = 22
local FONT_BTN       = 18
local PADDING        = 18

-- def = {
--   title    = "Confirm",
--   body     = "text or array of lines",
--   buttons  = { { id="cancel", label="Cancel" }, { id="ok", label="Launch anyway", disabled=false } },
-- }
function M.render(def, screen_w, screen_h)
    -- Backdrop.
    engine.render.draw_rect(0, 0, screen_w, screen_h, COLOR_BACKDROP)

    local w, h = math.min(screen_w - 80, 480), 0
    -- Compute height: title + body-lines + buttons-row.
    local body_lines = type(def.body) == "table" and def.body or { def.body or "" }
    h = PADDING * 4 + FONT_TITLE + #body_lines * (FONT_BTN + 4) + 40
    local x = (screen_w - w) / 2
    local y = (screen_h - h) / 2
    engine.render.draw_rect(x, y, w, h, COLOR_BG)
    engine.render.draw_text(def.title, x + PADDING, y + PADDING, FONT_TITLE, COLOR_TEXT)
    local cur_y = y + PADDING + FONT_TITLE + PADDING
    for _, line in ipairs(body_lines) do
        engine.render.draw_text(line, x + PADDING, cur_y, FONT_BTN, COLOR_TEXT)
        cur_y = cur_y + FONT_BTN + 4
    end
    -- Buttons row at the bottom.
    local btn_w = (w - PADDING * (#def.buttons + 1)) / #def.buttons
    local btn_y = y + h - PADDING - 32
    for i, b in ipairs(def.buttons) do
        local bx = x + PADDING + (i - 1) * (btn_w + PADDING)
        engine.render.draw_rect(bx, btn_y, btn_w, 32, b.disabled and 0x303030FF or COLOR_BTN)
        local lw, lh = engine.render.measure_text(b.label, FONT_BTN)
        engine.render.draw_text(b.label,
            bx + (btn_w - lw) / 2, btn_y + (32 - lh) / 2, FONT_BTN, COLOR_TEXT)
        b.rect = { x = bx, y = btn_y, w = btn_w, h = 32 }
    end
end

function M.handle_click(def, mx, my)
    for _, b in ipairs(def.buttons) do
        if not b.disabled and b.rect
            and engine.spatial.aabb_contains_point(b.rect, mx, my) then
            return b.id
        end
    end
    return nil
end

return M