/*
 * Copyright 2016 Nathan Fiedler
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

use std::error::Error;
use std::fs::File;
use std::io::prelude::*;
use std::path::Path;
use std::process::Command;

static HEADER: &'static str = "#include <wand/MagickWand.h>\n";

fn main() {
    //
    // If the MagickWand bindings are missing, generate them using
    // rust-bindgen.
    //
    let bindings_path = Path::new("src/bindings.rs");
    if !bindings_path.exists() {
        let bindgen_path = Path::new("rust-bindgen");
        if !bindgen_path.exists() {
            Command::new("git")
                    .arg("clone")
                    .arg("https://github.com/crabtw/rust-bindgen.git")
                    .status().unwrap();
            // Checkout a version of rust-bindgen that is known to work;
            // more recent versions produce code that does not compile (the
            // commit after 8a51860 changes the way enums are generated).
            Command::new("git")
                    .arg("checkout")
                    .arg("8a51860")
                    .current_dir("rust-bindgen")
                    .status().unwrap();
            Command::new("cargo")
                    .arg("build")
                    .current_dir("rust-bindgen")
                    .status().unwrap();
        }
        // Create the header file that rust-bindgen needs as input.
        let mut gen_h = match File::create("gen.h") {
            Err(why) => panic!("could not create gen.h file: {}", Error::description(&why)),
            Ok(file) => file
        };
        match gen_h.write_all(HEADER.as_bytes()) {
            Err(why) => panic!("could not write to gen.h: {}", Error::description(&why)),
            Ok(_)    => ()
        };
        // Get the compiler and linker flags for the MagickWand library.
        let mw_cflags_output = Command::new("MagickWand-config")
                .arg("--cflags")
                .output().unwrap();
        let mw_cflags = std::str::from_utf8(&mw_cflags_output.stdout).unwrap().trim();
        let mw_cflags_arr: Vec<&str> = mw_cflags.split_whitespace().collect();
        let mw_ldflags_output = Command::new("MagickWand-config")
                .arg("--ldflags")
                .output().unwrap();
        let mw_ldflags = std::str::from_utf8(&mw_ldflags_output.stdout).unwrap().trim();
        let mw_ldflags_arr: Vec<&str> = mw_ldflags.split_whitespace().collect();
        // Combine all of that in the invocation of rust-bindgen.
        Command::new("./rust-bindgen/target/debug/bindgen")
                // always include this even though it only makes sense on Mac to
                // work around https://github.com/crabtw/rust-bindgen/issues/89
                .env("DYLD_LIBRARY_PATH", "/Library/Developer/CommandLineTools/usr/lib")
                .args(&mw_cflags_arr[..])
                .arg("-builtins")
                .arg("-o")
                .arg("src/bindings.rs")
                .args(&mw_ldflags_arr[..])
                .arg("gen.h")
                .status().unwrap();
        // how to get the output of the command...
        // let output = Commad::new(...).output().unwrap();
        // let out = std::str::from_utf8(&output.stdout).unwrap();
        // println!("cargo:output={}", out);
        // let err = std::str::from_utf8(&output.stderr).unwrap();
        // println!("cargo:error={}", err);
        match std::fs::remove_file("gen.h") {
            Err(why) => panic!("could not remove gen.h: {}", Error::description(&why)),
            Ok(_)    => ()
        }
    }
    // For the sake of easily building and testing on Mac, include the path
    // to MagickWand. Chances are MagickWand is in /usr/local/lib, or
    // somewhere else that rustc can find it.
    println!("cargo:rustc-link-search=native=/usr/local/lib");
}