# A script to help generate build files on different platforms

# The Makefile generator

(def- make-cflags @["-std=c99" "-Wall" "-Wextra" "-O2" "-shared" "-fpic"])
(def- make-ldflags @[])

(if (= :macos (os.which))
  (array.push make-cflags "undefined -dynamic_lookup"))

(defn- $
  "Do and get the value of a subshell command"
  [command]
  (def f (file.popen command))
  (def ret (file.read f :all))
  (file.close f)
  ret)

(defn- emit-rule
  "Emit a rule in a makefile"
  @[out target deps recipe]
  (default recipe "@echo '-----'")
  (file.write
    out 
    target 
    ": " 
    (if (indexed? deps) (string.join deps " ") deps) 
    "\n\t"
    (if (indexed? recipe) (string.join recipe "\n\t") recipe)
    "\n\n")
  out)

(defn- generate-make
  "Generate a makefile"
  [out-path sources target]
  (def out (file.open out-path :w))
  (def csources (filter (fn [x] (= ".c" (string.slice x -2))) sources))
  (def hsources (filter (fn [x] (= ".h" (string.slice x -2))) sources))
  (file.write
    out
    "# Autogenerated Makefile, do not edit\n"
    "# Generated at " ($ `date`)
    "\nCFLAGS:=" (string.join make-cflags " ")
    "\nLDFLAGS:=" (string.join make-ldflags " ")
    "\nSOURCES:=" (string.join csources " ")
    "\nHEADERS:=" (string.join hsources " ")
    "\nOBJECTS:=$(patsubst %.c,%.o,${SOURCES})"
    "\nTARGET:=" target ".so"
    "\n\n")
  (emit-rule out "all" "${TARGET}")
  (emit-rule out "%.o" @["%.c" "${HEADERS}"] "${CC} ${CFLAGS} -o $@ $< ${LDFLAGS}")
  (emit-rule out "${TARGET}" "${OBJECTS}" "${CC} ${CFLAGS} -o $@ $^ ${LDFLAGS}")
  (emit-rule out "clean" "" "rm ${OBJECTS}")
  (emit-rule out "clean" "" @["rm ${OBJECTS}" "rm @{TARGET}"])
  # Phony targets
  (emit-rule out ".PHONY" @["all" "clean"])
  nil)

# The batch script generator (windows)

(defn- batch-crule
  "Create a snippet to compile a single C file to an .obj file"
  [file-path]
  (string 
    `cl /nologo /I..\..\src\include /c /O2 /W3 `
    file-path
    "\n@if errorlevel 1 goto :BUILDFAIL"))

(defn- generate-batch
  "Generate a batch file for windows"
  [out-path sources target]
  (def out (file.open out-path :w))
  (def csources (filter (fn [x] (= ".c" (string.slice x -2))) sources))
  (file.write
    out
    "@rem Generated batch script, run in 'Visual Studio Developer Prompt'\n"
    "\n@rem \n\n"
    "@echo off\n\n"
    (string.join (map batch-crule csources) "\n\n")
    "\n\n"
    `link /nologo /dll ..\..\dst.lib /out:` target `.dll *.obj`
    "\nif errorlevel 1 goto :BUILDFAIL"
    "\n\n@echo .\n@echo ======\n@echo Build Succeeded.\n@echo =====\n"
    "exit /b 0\n\n"
    ":BUILDFAIL\n"
    "@echo .\n"
    "@echo =====\n"
    "@echo BUILD FAILED. See Output For Details.\n"
    "@echo =====\n"
    "@echo .\n"
    "exit /b 1\n")
  (file.flush out)
  (file.close out)
  nil)

(defn generate
  "Generate the build files for a given library."
  [out-path sources target]
  ((if (= :windows (os.which)) generate-batch generate-make)
    out-path
    sources
    target))