#[cfg(not(target_env = "msvc"))]
extern crate pkg_config;

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

use std::env;
use std::fmt::{self, Display};
use std::path::PathBuf;
use std::process::Command;

enum LinkType {
    Static,
    Dynamic,
}

impl Display for LinkType {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            LinkType::Static => write!(f, "static"),
            LinkType::Dynamic => write!(f, "dylib"),
        }
    }
}

struct LinkingOptions {
    linking_type: Option<LinkType>,
    lib_name: &'static str,
}

impl LinkingOptions {
    fn from_name_and_type(lib_name: &'static str, tpe: LinkType) -> Self {
        LinkingOptions {
            linking_type: Some(tpe),
            lib_name,
        }
    }
    fn from_name(lib_name: &'static str) -> Self {
        LinkingOptions {
            linking_type: None,
            lib_name,
        }
    }

    fn from_env() -> Self {
        // On Windows-MSVC, always link dynamically
        if cfg!(all(windows, target_env = "msvc")) {
            return LinkingOptions::from_name_and_type("libpq", LinkType::Dynamic);
        }

        // Link unconditionally statically
        if env::var_os("PQ_LIB_STATIC").is_some() {
            return LinkingOptions::from_name_and_type("pq", LinkType::Static);
        }

        // Examine the per-target env vars
        if let Ok(target) = env::var("TARGET") {
            let pg_config_for_target = format!(
                "PQ_LIB_STATIC_{}",
                target.to_ascii_uppercase().replace('-', "_")
            );
            println!("cargo:rerun-if-env-changed={pg_config_for_target}");
            if env::var_os(&pg_config_for_target).is_some() {
                return LinkingOptions::from_name_and_type("pq", LinkType::Static);
            }
        }

        // Otherwise, don't specify
        LinkingOptions::from_name("pq")
    }
}

impl Display for LinkingOptions {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        if let Some(ref t) = self.linking_type {
            write!(f, "{t}=")?;
        }
        write!(f, "{}", self.lib_name)
    }
}

fn main() {
    bindgen();

    println!("cargo:rerun-if-env-changed=PQ_LIB_DIR");
    println!("cargo:rerun-if-env-changed=PQ_LIB_STATIC");
    println!("cargo:rerun-if-env-changed=TARGET");

    if let Ok(lib_dir) = env::var("PQ_LIB_DIR") {
        println!("cargo:rustc-link-search=native={lib_dir}");
    } else if configured() {
        return; // pkg_config and vcpkg does everything for us, including output for cargo
    } else if let Some(path) = pg_config_output("--libdir") {
        let path = replace_homebrew_path_on_mac(path);
        println!("cargo:rustc-link-search=native={path}");
    }
    println!("cargo:rustc-link-lib={}", LinkingOptions::from_env());
}

fn bindgen() {
    println!("cargo:rerun-if-changed=wrapper.h");

    let bindings = bindgen::Builder::default()
        .rustified_enum(".*")
        .clang_arg(format!(
            "-I{}",
            pg_config_output("--includedir").unwrap_or_else(|| "/usr/include".to_string())
        ))
        .header("wrapper.h")
        .generate()
        .expect("Unable to generate bindings");

    let out_path = std::path::PathBuf::from(std::env::var("OUT_DIR").unwrap());
    bindings
        .write_to_file(out_path.join("bindings.rs"))
        .expect("Couldn't write bindings!");
}

#[cfg(not(target_env = "msvc"))]
fn configured() -> bool {
    pkg_config::probe_library("libpq").is_ok()
}

#[cfg(target_env = "msvc")]
fn configured() -> bool {
    vcpkg::probe_package("libpq")
        .map(|_| {
            // found libpq which depends on openssl
            vcpkg::Config::new().find_package("openssl").ok();

            println!("cargo:rustc-link-lib=crypt32");
            println!("cargo:rustc-link-lib=gdi32");
            println!("cargo:rustc-link-lib=user32");
            println!("cargo:rustc-link-lib=secur32");
        })
        .is_ok()
}

fn pg_config_path() -> PathBuf {
    if let Ok(target) = env::var("TARGET") {
        let pg_config_for_target = &format!(
            "PG_CONFIG_{}",
            target.to_ascii_uppercase().replace('-', "_")
        );
        println!("cargo:rerun-if-env-changed={pg_config_for_target}");
        if let Some(pg_config_path) = env::var_os(pg_config_for_target) {
            let path = PathBuf::from(&pg_config_path);

            if !path.exists() {
                panic!("pg_config doesn't exist in the configured path: {path:?}");
            }

            return path;
        }
    }
    PathBuf::from("pg_config")
}

fn pg_config_output(command: &str) -> Option<String> {
    Command::new(pg_config_path())
        .arg(command)
        .output()
        .ok()
        .into_iter()
        .filter(|output| output.status.success())
        .flat_map(|output| String::from_utf8(output.stdout).ok())
        .map(|output| output.trim().to_string())
        .next()
}

#[cfg(not(target_os = "macos"))]
fn replace_homebrew_path_on_mac(path: String) -> String {
    path
}

#[cfg(target_os = "macos")]
fn replace_homebrew_path_on_mac(path: String) -> String {
    if path == "/usr/local/lib" {
        Command::new("brew")
            .arg("--prefix")
            .arg("postgres")
            .output()
            .ok()
            .into_iter()
            .filter(|output| output.status.success())
            .flat_map(|output| String::from_utf8(output.stdout).ok())
            .map(|output| format!("{}/lib", output.trim()))
            .next()
            .unwrap_or(path)
    } else {
        path
    }
}