use std::env;
use std::path::Path;

fn main() {
    let out_dir = env::var("OUT_DIR").unwrap();
    let out_path = Path::new(&out_dir).join("bindgen.rs");
    if cfg!(feature = "sqlcipher") {
        if cfg!(any(
            feature = "bundled",
            all(windows, feature = "bundled-windows")
        )) {
            println!(
                "cargo:warning={}",
                "Builds with bundled SQLCipher are not supported. Searching for SQLCipher to link against. \
                 This can lead to issues if your version of SQLCipher is not up to date!");
        }
        build_linked::main(&out_dir, &out_path)
    } else {
        // This can't be `cfg!` without always requiring our `mod build_bundled` (and
        // thus `cc`)
        #[cfg(any(feature = "bundled", all(windows, feature = "bundled-windows")))]
        {
            build_bundled::main(&out_dir, &out_path)
        }
        #[cfg(not(any(feature = "bundled", all(windows, feature = "bundled-windows"))))]
        {
            build_linked::main(&out_dir, &out_path)
        }
    }
}

#[cfg(any(feature = "bundled", all(windows, feature = "bundled-windows")))]
mod build_bundled {
    use cc;
    use std::env;
    use std::path::Path;

    pub fn main(out_dir: &str, out_path: &Path) {
        if cfg!(feature = "sqlcipher") {
            // This is just a sanity check, the top level `main` should ensure this.
            panic!("Builds with bundled SQLCipher are not supported");
        }

        #[cfg(feature = "buildtime_bindgen")]
        {
            use super::{bindings, HeaderLocation};
            let header = HeaderLocation::FromPath("sqlite3/sqlite3.h".to_owned());
            bindings::write_to_out_dir(header, out_path);
        }
        #[cfg(not(feature = "buildtime_bindgen"))]
        {
            use std::fs;
            fs::copy("sqlite3/bindgen_bundled_version.rs", out_path)
                .expect("Could not copy bindings to output directory");
        }

        let mut cfg = cc::Build::new();
        cfg.file("sqlite3/sqlite3.c")
            .flag("-DSQLITE_CORE")
            .flag("-DSQLITE_DEFAULT_FOREIGN_KEYS=1")
            .flag("-DSQLITE_ENABLE_API_ARMOR")
            .flag("-DSQLITE_ENABLE_COLUMN_METADATA")
            .flag("-DSQLITE_ENABLE_DBSTAT_VTAB")
            .flag("-DSQLITE_ENABLE_FTS3")
            .flag("-DSQLITE_ENABLE_FTS3_PARENTHESIS")
            .flag("-DSQLITE_ENABLE_FTS5")
            .flag("-DSQLITE_ENABLE_JSON1")
            .flag("-DSQLITE_ENABLE_LOAD_EXTENSION=1")
            .flag("-DSQLITE_ENABLE_MEMORY_MANAGEMENT")
            .flag("-DSQLITE_ENABLE_RTREE")
            .flag("-DSQLITE_ENABLE_STAT2")
            .flag("-DSQLITE_ENABLE_STAT4")
            .flag("-DSQLITE_SOUNDEX")
            .flag("-DSQLITE_THREADSAFE=1")
            .flag("-DSQLITE_USE_URI")
            .flag("-DHAVE_USLEEP=1");
        // Older versions of visual studio don't support c99 (including isnan), which
        // causes a build failure when the linker fails to find the `isnan`
        // function. `sqlite` provides its own implmentation, using the fact
        // that x != x when x is NaN.
        //
        // There may be other platforms that don't support `isnan`, they should be
        // tested for here.
        if cfg!(target_env = "msvc") {
            use cc::windows_registry::{find_vs_version, VsVers};
            let vs_has_nan = match find_vs_version() {
                Ok(ver) => ver != VsVers::Vs12,
                Err(_msg) => false,
            };
            if vs_has_nan {
                cfg.flag("-DSQLITE_HAVE_ISNAN");
            }
        } else {
            cfg.flag("-DSQLITE_HAVE_ISNAN");
        }
        if cfg!(feature = "unlock_notify") {
            cfg.flag("-DSQLITE_ENABLE_UNLOCK_NOTIFY");
        }
        if cfg!(feature = "preupdate_hook") {
            cfg.flag("-DSQLITE_ENABLE_PREUPDATE_HOOK");
        }
        if cfg!(feature = "session") {
            cfg.flag("-DSQLITE_ENABLE_SESSION");
        }

        if let Ok(limit) = env::var("SQLITE_MAX_VARIABLE_NUMBER") {
            cfg.flag(&format!("-DSQLITE_MAX_VARIABLE_NUMBER={}", limit));
        }
        println!("cargo:rerun-if-env-changed=SQLITE_MAX_VARIABLE_NUMBER");

        if let Ok(limit) = env::var("SQLITE_MAX_EXPR_DEPTH") {
            cfg.flag(&format!("-DSQLITE_MAX_EXPR_DEPTH={}", limit));
        }
        println!("cargo:rerun-if-env-changed=SQLITE_MAX_EXPR_DEPTH");

        cfg.compile("libsqlite3.a");

        println!("cargo:lib_dir={}", out_dir);
    }
}

fn env_prefix() -> &'static str {
    if cfg!(feature = "sqlcipher") {
        "SQLCIPHER"
    } else {
        "SQLITE3"
    }
}

pub enum HeaderLocation {
    FromEnvironment,
    Wrapper,
    FromPath(String),
}

impl From<HeaderLocation> for String {
    fn from(header: HeaderLocation) -> String {
        match header {
            HeaderLocation::FromEnvironment => {
                let prefix = env_prefix();
                let mut header = env::var(format!("{}_INCLUDE_DIR", prefix)).unwrap_or_else(|_| {
                    panic!(
                        "{}_INCLUDE_DIR must be set if {}_LIB_DIR is set",
                        prefix, prefix
                    )
                });
                header.push_str("/sqlite3.h");
                header
            }
            HeaderLocation::Wrapper => "wrapper.h".into(),
            HeaderLocation::FromPath(path) => path,
        }
    }
}

mod build_linked {
    use pkg_config;

    #[cfg(all(feature = "vcpkg", target_env = "msvc"))]
    extern crate vcpkg;

    use super::{bindings, env_prefix, HeaderLocation};
    use std::env;
    use std::path::Path;

    pub fn main(_out_dir: &str, out_path: &Path) {
        let header = find_sqlite();
        if cfg!(any(
            feature = "bundled_bindings",
            feature = "bundled",
            all(windows, feature = "bundled-windows")
        )) && !cfg!(feature = "buildtime_bindgen")
        {
            // Generally means the `bundled_bindings` feature is enabled
            // (there's also an edge case where we get here involving
            // sqlcipher). In either case most users are better off with turning
            // on buildtime_bindgen instead, but this is still supported as we
            // have runtime version checks and there are good reasons to not
            // want to run bindgen.
            std::fs::copy("sqlite3/bindgen_bundled_version.rs", out_path)
                .expect("Could not copy bindings to output directory");
        } else {
            bindings::write_to_out_dir(header, out_path);
        }
    }

    fn find_link_mode() -> &'static str {
        // If the user specifies SQLITE_STATIC (or SQLCIPHER_STATIC), do static
        // linking, unless it's explicitly set to 0.
        match &env::var(format!("{}_STATIC", env_prefix())) {
            Ok(v) if v != "0" => "static",
            _ => "dylib",
        }
    }
    // Prints the necessary cargo link commands and returns the path to the header.
    fn find_sqlite() -> HeaderLocation {
        let link_lib = link_lib();

        println!("cargo:rerun-if-env-changed={}_INCLUDE_DIR", env_prefix());
        println!("cargo:rerun-if-env-changed={}_LIB_DIR", env_prefix());
        println!("cargo:rerun-if-env-changed={}_STATIC", env_prefix());
        if cfg!(all(feature = "vcpkg", target_env = "msvc")) {
            println!("cargo:rerun-if-env-changed=VCPKGRS_DYNAMIC");
        }

        // dependents can access `DEP_SQLITE3_LINK_TARGET` (`sqlite3` being the
        // `links=` value in our Cargo.toml) to get this value. This might be
        // useful if you need to ensure whatever crypto library sqlcipher relies
        // on is available, for example.
        println!("cargo:link-target={}", link_lib);

        // Allow users to specify where to find SQLite.
        if let Ok(dir) = env::var(format!("{}_LIB_DIR", env_prefix())) {
            // Try to use pkg-config to determine link commands
            let pkgconfig_path = Path::new(&dir).join("pkgconfig");
            env::set_var("PKG_CONFIG_PATH", pkgconfig_path);
            if pkg_config::Config::new().probe(link_lib).is_err() {
                // Otherwise just emit the bare minimum link commands.
                println!("cargo:rustc-link-lib={}={}", find_link_mode(), link_lib);
                println!("cargo:rustc-link-search={}", dir);
            }
            return HeaderLocation::FromEnvironment;
        }

        if let Some(header) = try_vcpkg() {
            return header;
        }

        // See if pkg-config can do everything for us.
        match pkg_config::Config::new()
            .print_system_libs(false)
            .probe(link_lib)
        {
            Ok(mut lib) => {
                if let Some(mut header) = lib.include_paths.pop() {
                    header.push("sqlite3.h");
                    HeaderLocation::FromPath(header.to_string_lossy().into())
                } else {
                    HeaderLocation::Wrapper
                }
            }
            Err(_) => {
                // No env var set and pkg-config couldn't help; just output the link-lib
                // request and hope that the library exists on the system paths. We used to
                // output /usr/lib explicitly, but that can introduce other linking problems;
                // see https://github.com/jgallagher/rusqlite/issues/207.
                println!("cargo:rustc-link-lib={}={}", find_link_mode(), link_lib);
                HeaderLocation::Wrapper
            }
        }
    }

    #[cfg(all(feature = "vcpkg", target_env = "msvc"))]
    fn try_vcpkg() -> Option<HeaderLocation> {
        // See if vcpkg can find it.
        if let Ok(mut lib) = vcpkg::Config::new().probe(link_lib()) {
            if let Some(mut header) = lib.include_paths.pop() {
                header.push("sqlite3.h");
                return Some(HeaderLocation::FromPath(header.to_string_lossy().into()));
            }
        }
        None
    }

    #[cfg(not(all(feature = "vcpkg", target_env = "msvc")))]
    fn try_vcpkg() -> Option<HeaderLocation> {
        None
    }

    fn link_lib() -> &'static str {
        if cfg!(feature = "sqlcipher") {
            "sqlcipher"
        } else {
            "sqlite3"
        }
    }
}

#[cfg(not(feature = "buildtime_bindgen"))]
mod bindings {
    use super::HeaderLocation;

    use std::fs;
    use std::path::Path;

    static PREBUILT_BINDGEN_PATHS: &'static [&'static str] = &[
        "bindgen-bindings/bindgen_3.6.8.rs",
        #[cfg(feature = "min_sqlite_version_3_6_23")]
        "bindgen-bindings/bindgen_3.6.23.rs",
        #[cfg(feature = "min_sqlite_version_3_7_7")]
        "bindgen-bindings/bindgen_3.7.7.rs",
        #[cfg(feature = "min_sqlite_version_3_7_16")]
        "bindgen-bindings/bindgen_3.7.16.rs",
    ];

    pub fn write_to_out_dir(_header: HeaderLocation, out_path: &Path) {
        let in_path = PREBUILT_BINDGEN_PATHS[PREBUILT_BINDGEN_PATHS.len() - 1];
        fs::copy(in_path, out_path).expect("Could not copy bindings to output directory");
    }
}

#[cfg(feature = "buildtime_bindgen")]
mod bindings {
    use bindgen;

    use super::HeaderLocation;
    use bindgen::callbacks::{IntKind, ParseCallbacks};

    use std::fs::OpenOptions;
    use std::io::Write;
    use std::path::Path;

    #[derive(Debug)]
    struct SqliteTypeChooser;

    impl ParseCallbacks for SqliteTypeChooser {
        fn int_macro(&self, _name: &str, value: i64) -> Option<IntKind> {
            if value >= i32::min_value() as i64 && value <= i32::max_value() as i64 {
                Some(IntKind::I32)
            } else {
                None
            }
        }
    }

    pub fn write_to_out_dir(header: HeaderLocation, out_path: &Path) {
        let header: String = header.into();
        let mut output = Vec::new();
        let mut bindings = bindgen::builder()
            .header(header.clone())
            .parse_callbacks(Box::new(SqliteTypeChooser))
            .rustfmt_bindings(true);

        if cfg!(feature = "unlock_notify") {
            bindings = bindings.clang_arg("-DSQLITE_ENABLE_UNLOCK_NOTIFY");
        }
        if cfg!(feature = "preupdate_hook") {
            bindings = bindings.clang_arg("-DSQLITE_ENABLE_PREUPDATE_HOOK");
        }
        if cfg!(feature = "session") {
            bindings = bindings.clang_arg("-DSQLITE_ENABLE_SESSION");
        }

        bindings
            .generate()
            .unwrap_or_else(|_| panic!("could not run bindgen on header {}", header))
            .write(Box::new(&mut output))
            .expect("could not write output of bindgen");
        let mut output = String::from_utf8(output).expect("bindgen output was not UTF-8?!");

        // rusqlite's functions feature ors in the SQLITE_DETERMINISTIC flag when it
        // can. This flag was added in SQLite 3.8.3, but oring it in in prior
        // versions of SQLite is harmless. We don't want to not build just
        // because this flag is missing (e.g., if we're linking against
        // SQLite 3.7.x), so append the flag manually if it isn't present in bindgen's
        // output.
        if !output.contains("pub const SQLITE_DETERMINISTIC") {
            output.push_str("\npub const SQLITE_DETERMINISTIC: i32 = 2048;\n");
        }

        let mut file = OpenOptions::new()
            .write(true)
            .truncate(true)
            .create(true)
            .open(out_path)
            .unwrap_or_else(|_| panic!("Could not write to {:?}", out_path));

        file.write_all(output.as_bytes())
            .unwrap_or_else(|_| panic!("Could not write to {:?}", out_path));
    }
}