// Run: make test-cpp
// The rect and hit assertions from test/ui_layout.lua, against the C++ node arena.
// Panel and font match test/fake_device.lua so the numbers are the same ones.

#include "../src/ui/layout.h"

#include <cstdio>
#include <cstring>
#include <string>

using namespace ui;

static const int PANEL_W = 320, PANEL_H = 480;
static const int CHAR_W = 6, FONT_H = 8;

static int failures = 0;

static void check(const char* what, const std::string& got, const std::string& want) {
  if (got == want) return;
  printf("\n  %s: got %s, want %s", what, got.c_str(), want.c_str());
  failures++;
}

static void checkTrue(const char* what, bool ok) {
  if (ok) return;
  printf("\n  %s", what);
  failures++;
}

static std::string rect(const Tree& tree, uint16_t id) {
  const Node& n = tree.nodes[id];
  char buffer[64];
  snprintf(buffer, sizeof(buffer), "%d,%d %dx%d", n.x, n.y, n.w, n.h);
  return buffer;
}

// Builders -----------------------------------------------------------------

static Spec boxSpec() { return Spec(); }

static Spec textSpec(const char* label) {
  Spec spec;
  spec.intrinsicW = static_cast<int16_t>(strlen(label) * CHAR_W);
  spec.intrinsicH = FONT_H;
  return spec;
}

static uint16_t addText(Tree& tree, uint16_t parent, const char* label) {
  uint16_t id = tree.add(parent, textSpec(label), TEXT);
  tree.setLabel(id, label);
  return id;
}

// Mirrors ui.button: pad 8 all round, contents centred on the cross axis.
static uint16_t addButton(Tree& tree, uint16_t parent, const char* label, bool interactive = true) {
  Spec spec;
  spec.padT = spec.padR = spec.padB = spec.padL = 8;
  spec.align = CENTER;
  uint16_t id = tree.add(parent, spec, BUTTON, interactive ? INTERACTIVE : 0);
  addText(tree, id, label);
  return id;
}

// Mirrors ui.screen: the root is the panel, so it must measure that way too.
static uint16_t addRoot(Tree& tree, Spec spec = Spec()) {
  spec.w = Size::fill();
  spec.h = Size::fill();
  return tree.add(NONE, spec);
}

static bool run(Tree& tree, uint16_t root) {
  return tree.layout(root, 0, 0, PANEL_W, PANEL_H);
}

// Cases --------------------------------------------------------------------

static void flowStacksChildren() {
  Tree tree;
  Spec spec;
  spec.padT = spec.padR = spec.padB = spec.padL = 12;
  spec.gap = 8;
  uint16_t root = addRoot(tree, spec);
  uint16_t title = addText(tree, root, "settings");
  uint16_t first = addButton(tree, root, "one");
  uint16_t second = addButton(tree, root, "two");

  checkTrue("flow laid out", run(tree, root));
  check("title", rect(tree, title), "12,12 296x8");
  // Button height is text plus its own padding: 8 + 8 + 8 = 24.
  check("first button", rect(tree, first), "12,28 296x24");
  check("second button", rect(tree, second), "12,60 296x24");
}

static void fractionsResolveAgainstContent() {
  Tree tree;
  Spec spec;
  spec.padT = spec.padR = spec.padB = spec.padL = 10;
  uint16_t root = addRoot(tree, spec);

  Spec halfSpec = boxSpec();
  halfSpec.w = Size::fraction(500);
  halfSpec.h = Size::px(40);
  uint16_t half = tree.add(root, halfSpec);

  Spec fixedSpec = boxSpec();
  fixedSpec.w = Size::px(100);
  fixedSpec.h = Size::px(40);
  uint16_t fixed = tree.add(root, fixedSpec);

  checkTrue("fractions laid out", run(tree, root));
  check("half", rect(tree, half), "10,10 150x40");
  check("fixed", rect(tree, fixed), "10,50 100x40");
}

static void rowCentresOnCrossAxis() {
  Tree tree;
  uint16_t root = addRoot(tree);

  Spec rowSpec;
  rowSpec.gap = 6;
  rowSpec.align = CENTER;
  rowSpec.h = Size::px(40);
  uint16_t row = tree.add(root, rowSpec, BOX, ROW);

  Spec tallSpec;
  tallSpec.w = Size::px(40);
  tallSpec.h = Size::px(40);
  uint16_t tall = tree.add(row, tallSpec);

  Spec shortSpec;
  shortSpec.w = Size::px(40);
  shortSpec.h = Size::px(10);
  uint16_t shortBox = tree.add(row, shortSpec);

  checkTrue("row laid out", run(tree, root));
  check("tall", rect(tree, tall), "0,0 40x40");
  check("short", rect(tree, shortBox), "46,15 40x10");
}

// justify distributes the main axis: "between" pushes the last child to the far edge,
// which is how a header keeps a title left and a clock right without arithmetic.
static void justifyBetweenSpreads() {
  Tree tree;
  Spec rootSpec;
  rootSpec.padT = rootSpec.padR = rootSpec.padB = rootSpec.padL = 10;
  uint16_t root = addRoot(tree, rootSpec);

  Spec rowSpec;
  rowSpec.justify = BETWEEN;
  uint16_t row = tree.add(root, rowSpec, BOX, ROW);

  Spec leftSpec;
  leftSpec.w = Size::px(40);
  leftSpec.h = Size::px(10);
  uint16_t left = tree.add(row, leftSpec);

  Spec rightSpec;
  rightSpec.w = Size::px(60);
  rightSpec.h = Size::px(10);
  uint16_t right = tree.add(row, rightSpec);

  checkTrue("between laid out", run(tree, root));
  check("left", rect(tree, left), "10,10 40x10");
  check("right", rect(tree, right), "250,10 60x10");
}

// The other modes shift the whole run rather than spreading it.
static void justifyEndShiftsRun() {
  Tree tree;
  uint16_t root = addRoot(tree);

  Spec rowSpec;
  rowSpec.gap = 10;
  rowSpec.justify = END;
  uint16_t row = tree.add(root, rowSpec, BOX, ROW);

  Spec aSpec;
  aSpec.w = Size::px(40);
  aSpec.h = Size::px(10);
  uint16_t a = tree.add(row, aSpec);

  Spec bSpec;
  bSpec.w = Size::px(60);
  bSpec.h = Size::px(10);
  uint16_t b = tree.add(row, bSpec);

  checkTrue("end laid out", run(tree, root));
  check("a", rect(tree, a), "210,0 40x10");
  check("b", rect(tree, b), "260,0 60x10");
}

// One child cannot be spread against anything, so "between" degrades to "start".
static void betweenWithOneChild() {
  Tree tree;
  uint16_t root = addRoot(tree);

  Spec rowSpec;
  rowSpec.justify = BETWEEN;
  uint16_t row = tree.add(root, rowSpec, BOX, ROW);

  Spec onlySpec;
  onlySpec.w = Size::px(40);
  onlySpec.h = Size::px(10);
  uint16_t only = tree.add(row, onlySpec);

  checkTrue("lone child laid out", run(tree, root));
  check("only", rect(tree, only), "0,0 40x10");
}

// The root always fills the screen, so alignment there spans the whole panel.
static void alignCentresOnTheRoot() {
  Tree tree;
  Spec rootSpec;
  rootSpec.align = CENTER;
  uint16_t root = addRoot(tree, rootSpec);

  Spec loneSpec;
  loneSpec.w = Size::px(40);
  loneSpec.h = Size::px(40);
  uint16_t lone = tree.add(root, loneSpec);

  checkTrue("centred root laid out", run(tree, root));
  check("lone", rect(tree, lone), "140,0 40x40");
}

// A fraction inside an auto-sized parent is an error, not a silent zero.
static void fractionInsideAutoParentFails() {
  Tree tree;
  uint16_t root = addRoot(tree);
  uint16_t autoBox = tree.add(root, boxSpec());

  Spec childSpec;
  childSpec.w = Size::px(20);
  childSpec.h = Size::fraction(500);
  tree.add(autoBox, childSpec);

  checkTrue("fraction inside an auto parent must fail loudly", !run(tree, root));
}

// Hit testing: deepest interactive node wins over its tappable ancestor.
static void hitPrefersTheDeepestNode() {
  Tree tree;
  Spec outerSpec;
  outerSpec.padT = outerSpec.padR = outerSpec.padB = outerSpec.padL = 20;
  outerSpec.w = Size::fill();
  outerSpec.h = Size::fill();
  uint16_t outer = tree.add(NONE, outerSpec, BOX, INTERACTIVE);
  uint16_t inner = addButton(tree, outer, "inner");

  checkTrue("hit tree laid out", run(tree, outer));
  checkTrue("inner button should win inside its rect", tree.hit(outer, 160, 30) == inner);
  checkTrue("the container claims its own padding", tree.hit(outer, 2, 2) == outer);
  checkTrue("outside the tree is a miss", tree.hit(outer, -50, -50) == NONE);
}

// A dialog is an ordinary node the app includes, placed absolutely so it covers the flow
// and swallows the taps that would otherwise reach what is underneath it.
static void dialogCoversAndCaptures() {
  Tree tree;
  uint16_t root = addRoot(tree);

  Spec behindSpec;
  behindSpec.padT = behindSpec.padR = behindSpec.padB = behindSpec.padL = 12;
  uint16_t behind = tree.add(root, behindSpec);
  uint16_t buried = addButton(tree, behind, "do not press");

  Spec layerSpec;
  layerSpec.absolute = true;
  layerSpec.atX = Size::px(0);
  layerSpec.atY = Size::px(0);
  layerSpec.w = Size::fill();
  layerSpec.h = Size::fill();
  layerSpec.align = CENTER;
  layerSpec.justify = CENTER;
  uint16_t layer = tree.add(root, layerSpec, BOX, CAPTURE);

  Spec cardSpec;
  cardSpec.w = Size::fraction(850);
  cardSpec.padT = cardSpec.padR = cardSpec.padB = cardSpec.padL = 16;
  cardSpec.gap = 12;
  uint16_t card = tree.add(layer, cardSpec);
  addText(tree, card, "forget network?");

  Spec buttonsSpec;
  buttonsSpec.gap = 8;
  buttonsSpec.justify = END;
  uint16_t buttons = tree.add(card, buttonsSpec, BOX, ROW);
  addButton(tree, buttons, "cancel");
  uint16_t confirm = addButton(tree, buttons, "forget");

  checkTrue("dialog laid out", run(tree, root));
  check("layer", rect(tree, layer), "0,0 320x480");

  const Node& cardNode = tree.nodes[card];
  checkTrue("card is 0.85 of the panel", cardNode.w == 272);
  checkTrue("card is centred horizontally", cardNode.x == 24);
  checkTrue("card is centred vertically", cardNode.y == (PANEL_H - cardNode.h) / 2);

  checkTrue("the dialog was tapped through", tree.hit(root, 60, 24) == layer);
  checkTrue("the dialog's own buttons still work",
            tree.hit(root, tree.nodes[confirm].x + 4, tree.nodes[confirm].y + 4) == confirm);
  (void)buried;
}

// Labels share one arena. Overwriting in place matters because the clock repaints every
// second at a fixed width, and an append per tick would grow without bound.
static void labelsShareOneArena() {
  Tree tree;
  uint16_t root = addRoot(tree);
  uint16_t clock = addText(tree, root, "12:00:00");
  uint16_t other = addText(tree, root, "wifi");

  size_t before = tree.footprint();
  for (int i = 0; i < 100; i++) tree.setLabel(clock, "12:00:01");
  checkTrue("a same-width label must not grow the arena", tree.footprint() == before);
  check("clock label", tree.label(clock), "12:00:01");
  check("neighbour label", tree.label(other), "wifi");

  tree.setLabel(clock, "a much longer label");
  check("grown label", tree.label(clock), "a much longer label");
  check("neighbour survived the growth", tree.label(other), "wifi");
  checkTrue("a node with no label reports none", tree.label(root) == nullptr);
}

// Styling is inheritance rather than copies: the root carries the palette and a node
// that names nothing costs nothing, which is what keeps the arena at 16 bytes a node.
static void styleInheritsFromTheNearestAncestor() {
  Tree tree;
  uint16_t root = addRoot(tree);
  uint16_t middle = tree.add(root, boxSpec());
  uint16_t leaf = tree.add(middle, boxSpec());

  Style& palette = tree.styleFor(root);
  palette.fg = 0x0001;
  palette.bg = 0x0002;
  palette.set = S_FG | S_BG;

  Style& override_ = tree.styleFor(leaf);
  override_.fg = 0x0003;
  override_.set = S_FG;

  checkTrue("a leaf inherits what it does not state", tree.inherited(leaf, S_BG).bg == 0x0002);
  checkTrue("a leaf keeps what it does state", tree.inherited(leaf, S_FG).fg == 0x0003);
  checkTrue("an unstyled node inherits both", tree.inherited(middle, S_FG).fg == 0x0001);
  checkTrue("an unset role falls back rather than guessing",
            tree.inherited(leaf, S_BORDER).border == Style().border);
  checkTrue("only styled nodes cost anything", tree.styleOf(middle) == nullptr);
}

// The point of the split arena: what a screen costs once its layout pass is over.
static void reportFootprint() {
  Tree tree;
  uint16_t root = addRoot(tree);
  for (int i = 0; i < 200; i++) addButton(tree, root, "item");
  size_t built = tree.nodes.size();
  checkTrue("footprint tree laid out", run(tree, root));

  size_t scratch = built * sizeof(Spec);
  tree.dropScratch();
  size_t persistent = tree.footprint();
  printf("\n  sizeof(Node)=%zu sizeof(Spec)=%zu", sizeof(Node), sizeof(Spec));
  printf("\n  %zu nodes: %zu B steady, %zu B peak (+%zu B scratch)", built, persistent,
         persistent + scratch, scratch);

  checkTrue("a Node must stay at 16 bytes", sizeof(Node) == 16);
}

int main() {
  flowStacksChildren();
  fractionsResolveAgainstContent();
  rowCentresOnCrossAxis();
  justifyBetweenSpreads();
  justifyEndShiftsRun();
  betweenWithOneChild();
  alignCentresOnTheRoot();
  fractionInsideAutoParentFails();
  hitPrefersTheDeepestNode();
  dialogCoversAndCaptures();
  labelsShareOneArena();
  styleInheritsFromTheNearestAncestor();
  reportFootprint();

  if (failures) {
    printf("\n%d failure(s)\n", failures);
    return 1;
  }
  printf("\n  ok\n");
  return 0;
}