-- Check basic find_ray functionality.
local FAILMAP = 'losfail.map'
local checks = 0
local function test_losight_symmetry()
  -- Clear messages to prevent them accumulating and forcing a --more--
  crawl.mesclr()
  -- Send the player to a random spot on the level.
  you.random_teleport()
  -- Forcibly redo LOS.
  you.losight()
  checks = checks + 1
  local you_x, you_y = you.pos()
  local you_p = dgn.point(you_x, you_y)
  local visible_spots = { }
  for y = -8, 8 do
    for x = -8, 8 do
      if x ~= 0 or y ~= 0 then
        local px, py = x + you_x, y + you_y
        if you.see_grid(px, py) then
          table.insert(visible_spots, { px, py })
        end
      end
    end
  end
  -- For each position in LOS, shoot a ray there
  -- and make sure it doesn't go through an opaque cell.
  for _, spot in ipairs(visible_spots) do
    local x, y = unpack(spot)
    local p = dgn.point(x, y)
    local ray = los.findray(you_x, you_y, x, y)
    if not ray then
      dgn.grid(x, y, "floor_special")
      dgn.dbg_dump_map(FAILMAP)
      assert(false, "Can't find ray to " .. p ..
                    " although it's in view.")
    end
    local rx, ry = ray:pos()
    local ray_p = dgn.point(rx, ry)
    assert(ray_p == you_p,
           "Ray doesn't start at player position " .. you_p ..
           " but " .. ray_p .. ".")
    ray:advance()
    rx, ry = ray:pos()
    ray_p = dgn.point(rx, ry)
    while(ray_p ~= p) do
      if dgn.is_opaque(rx, ry) then
        dgn.grid(x, y, "floor_special")
        dgn.dbg_dump_map(FAILMAP)
        assert(false,
               "Ray from " .. you_p .. " to " .. p ..
               " passes through opaque cell " .. ray_p
               .. ".")
      end
      ray:advance()
      rx, ry = ray:pos()
      ray_p = dgn.point(rx, ry)
    end
  end
end
local function run_los_tests(depth, nlevels, tests_per_level)
  local place = "D:" .. depth
  crawl.mpr("Running LOS tests on " .. place)
  dgn.dbg_goto_place(place)
  for lev_i = 1, nlevels do
    dgn.dbg_flush_map_memory()
    dgn.dbg_generate_level()
    for t_i = 1, tests_per_level do
      test_losight_symmetry()
    end
  end
end
for depth = 1, 27 do
  run_los_tests(depth, 1, 10)
end