project('forts-clone', 'cpp',
  version: '0.1.0',
  license: 'GPL-3.0-or-later',
  default_options: [
    'cpp_std=c++20',
    'warning_level=3',
    'buildtype=debugoptimized',
    'default_library=static',
  ],
  meson_version: '>=1.4.0',
)

cpp = meson.get_compiler('cpp')

# =============================================================================
# Dependencies (pre-built in /usr/local by Containerfile)
# =============================================================================

fs = import('fs')

# A source-built /usr/local (what the container ships) provides the heavier
# libraries. On a stock system these paths are absent, so everything below falls
# back to system packages. include_directories() errors on a missing directory,
# hence the guard.
#
# NOTE: add /usr/local/include as a whole, never /usr/local/include/bx etc.
# individually. sys/types.h includes <endian.h>, which collides with bx's
# endian.h if -I.../include/bx is on the path.
local_incs = []
if fs.is_dir('/usr/local/include')
  local_incs += include_directories('/usr/local/include')
endif
usr_local_libdirs = ['/usr/local/lib64', '/usr/local/lib', '/usr/local/lib/static']

# --- Libraries the code actually compiles against ---------------------------

# SDL3 -- windowing + input. System pkg-config on every target.
sdl3_dep = dependency('sdl3', required: true)

# glm -- header-only math. pkg-config where available, else rely on the include
# path (headers in /usr/include or the guarded /usr/local/include).
glm_dep = dependency('glm', required: false)
if not glm_dep.found()
  glm_dep = declare_dependency()
endif

# sol2 -- header-only Lua bindings. Headers resolve via the include path
# (/usr/include/sol system/AUR, or /usr/local/include/sol in the container).
sol2_dep = declare_dependency()

# Lua 5.4. Container: a STATIC liblua.a in /usr/local/lib, so the binary carries
# Lua and runs on any host regardless of its liblua soname. Native build: the
# system Lua 5.4 (dynamic linking is fine when built and run on the same box).
lua_static = cpp.find_library('lua', dirs: ['/usr/local/lib'], static: true, required: false)
if lua_static.found()
  m_dep   = cpp.find_library('m',  required: false)
  dl_dep  = cpp.find_library('dl', required: false)
  lua_dep = declare_dependency(dependencies: [lua_static, m_dep, dl_dep])
else
  lua_dep = dependency('lua5.4', 'lua54', 'lua-5.4', required: false)
  if not lua_dep.found()
    lua_dep = dependency('lua', required: true)
  endif
endif

# Box2D v3 -- physics. Idle for now, but physics.cpp compiles against its header.
# Try /usr/local (container), then pkg-config/cmake, then a plain system lib.
box2d_dep = cpp.find_library('box2d', dirs: usr_local_libdirs, required: false)
if not box2d_dep.found()
  box2d_dep = dependency('box2d', required: false)
endif
if not box2d_dep.found()
  box2d_dep = cpp.find_library('box2d', required: true)
endif

# --- Declared but not yet wired up ------------------------------------------
# bgfx/SoLoud/ENet/EnTT belong to the planned stack, but no source file
# #includes them yet (the live renderer is SDL_Renderer; physics/audio/net are
# idle). Link them only if a source build has provided them; a stock system
# build simply skips them. Promote each to a real dependency when it is wired up.
optional_deps = []
foreach libname : ['bgfx', 'bimg', 'bx', 'soloud', 'enet']
  found = cpp.find_library(libname, dirs: usr_local_libdirs, required: false)
  if found.found()
    optional_deps += found
  endif
endforeach

# ImGui -- skipped for M0, added when debug UI is needed

# =============================================================================
# Engine library and executable
# =============================================================================

engine_inc = include_directories('src')
stb_inc    = include_directories('third_party/stb')

# Dear ImGui (dev UI) — built as its own lib with relaxed warnings.
imgui_inc = include_directories('third_party/imgui', 'third_party/imgui/backends')
imgui_lib = static_library('imgui',
  [
    'third_party/imgui/imgui.cpp',
    'third_party/imgui/imgui_draw.cpp',
    'third_party/imgui/imgui_tables.cpp',
    'third_party/imgui/imgui_widgets.cpp',
    'third_party/imgui/backends/imgui_impl_sdl3.cpp',
    'third_party/imgui/backends/imgui_impl_sdlrenderer3.cpp',
  ],
  include_directories: imgui_inc,
  dependencies: sdl3_dep,
  override_options: ['warning_level=0', 'werror=false'],
)
imgui_dep = declare_dependency(link_with: imgui_lib, include_directories: imgui_inc)

engine_src = [
  'src/engine/app.cpp',
  'src/engine/renderer.cpp',
  'src/engine/input.cpp',
  'src/engine/camera.cpp',
  'src/engine/physics.cpp',
  'src/engine/script.cpp',
  'src/engine/stb_impl.cpp',
  'src/game/build_graph.cpp',
  'src/game/data.cpp',
]

engine_deps = [
  sdl3_dep,
  box2d_dep,
  lua_dep,
  glm_dep,
  sol2_dep,
  imgui_dep,
] + optional_deps

extra_inc = local_incs + [stb_inc]

# Required by bx/bgfx (normally set by cmake targets; we need them manually
# since we link raw .a files).
# GCC 14+ on glibc: __BEGIN_DECLS from sys/types.h wraps bx endian.inl
# templates in extern "C". -fpermissive downgrades to warnings.
buildtype = get_option('buildtype')
bx_debug = buildtype.startswith('debug') ? '1' : '0'

extra_cpp_args = [
  '-msse4.2',
  '-DBX_CONFIG_DEBUG=@0@'.format(bx_debug),
  '-DBGFX_CONFIG_DEBUG_ANNOTATION=@0@'.format(bx_debug),
  '-DBGFX_CONFIG_MULTITHREADED=1',
  '-DBGFX_CONFIG_VIDEO=1',
  '-D__STDC_LIMIT_MACROS',
  '-D__STDC_FORMAT_MACROS',
  '-D__STDC_CONSTANT_MACROS',
]

engine_lib = static_library('engine', engine_src,
  include_directories: [engine_inc] + extra_inc,
  dependencies: engine_deps,
  cpp_args: extra_cpp_args,
)

executable('forts-clone', 'src/main.cpp',
  link_with: engine_lib,
  include_directories: [engine_inc] + extra_inc,
  dependencies: engine_deps,
  cpp_args: extra_cpp_args,
)