use std::ffi::OsStr;
use std::io::Write;
use std::path::Path;
use std::process::{Command, Output, Stdio};

use crate::{env_var, env_var_os, handle_failed_output, set_host_rpath};

/// Construct a plain `rustdoc` invocation with no flags set.
pub fn bare_rustdoc() -> Rustdoc {
    Rustdoc::bare()
}

/// Construct a new `rustdoc` invocation with `-L $(TARGET_RPATH_DIR)` set.
pub fn rustdoc() -> Rustdoc {
    Rustdoc::new()
}

#[derive(Debug)]
pub struct Rustdoc {
    cmd: Command,
    stdin: Option<Box<[u8]>>,
}

crate::impl_common_helpers!(Rustdoc);

fn setup_common() -> Command {
    let rustdoc = env_var("RUSTDOC");
    let mut cmd = Command::new(rustdoc);
    set_host_rpath(&mut cmd);
    cmd
}

impl Rustdoc {
    /// Construct a bare `rustdoc` invocation.
    pub fn bare() -> Self {
        let cmd = setup_common();
        Self { cmd, stdin: None }
    }

    /// Construct a `rustdoc` invocation with `-L $(TARGET_RPATH_DIR)` set.
    pub fn new() -> Self {
        let mut cmd = setup_common();
        let target_rpath_dir = env_var_os("TARGET_RPATH_DIR");
        cmd.arg(format!("-L{}", target_rpath_dir.to_string_lossy()));
        Self { cmd, stdin: None }
    }

    /// Specify where an external library is located.
    pub fn extern_<P: AsRef<Path>>(&mut self, crate_name: &str, path: P) -> &mut Self {
        assert!(
            !crate_name.contains(|c: char| c.is_whitespace() || c == '\\' || c == '/'),
            "crate name cannot contain whitespace or path separators"
        );

        let path = path.as_ref().to_string_lossy();

        self.cmd.arg("--extern");
        self.cmd.arg(format!("{crate_name}={path}"));

        self
    }

    /// Specify path to the input file.
    pub fn input<P: AsRef<Path>>(&mut self, path: P) -> &mut Self {
        self.cmd.arg(path.as_ref());
        self
    }

    /// Specify path to the output folder.
    pub fn output<P: AsRef<Path>>(&mut self, path: P) -> &mut Self {
        self.cmd.arg("-o");
        self.cmd.arg(path.as_ref());
        self
    }

    /// Specify output directory.
    pub fn out_dir<P: AsRef<Path>>(&mut self, path: P) -> &mut Self {
        self.cmd.arg("--out-dir").arg(path.as_ref());
        self
    }

    /// Given a `path`, pass `@{path}` to `rustdoc` as an
    /// [arg file](https://doc.rust-lang.org/rustdoc/command-line-arguments.html#path-load-command-line-flags-from-a-path).
    pub fn arg_file<P: AsRef<Path>>(&mut self, path: P) -> &mut Self {
        self.cmd.arg(format!("@{}", path.as_ref().display()));
        self
    }

    /// Specify a stdin input
    pub fn stdin<I: AsRef<[u8]>>(&mut self, input: I) -> &mut Self {
        self.cmd.stdin(Stdio::piped());
        self.stdin = Some(input.as_ref().to_vec().into_boxed_slice());
        self
    }

    /// Get the [`Output`] of the finished process.
    #[track_caller]
    pub fn command_output(&mut self) -> ::std::process::Output {
        // let's make sure we piped all the input and outputs
        self.cmd.stdin(Stdio::piped());
        self.cmd.stdout(Stdio::piped());
        self.cmd.stderr(Stdio::piped());

        if let Some(input) = &self.stdin {
            let mut child = self.cmd.spawn().unwrap();

            {
                let mut stdin = child.stdin.take().unwrap();
                stdin.write_all(input.as_ref()).unwrap();
            }

            child.wait_with_output().expect("failed to get output of finished process")
        } else {
            self.cmd.output().expect("failed to get output of finished process")
        }
    }

    /// Specify the edition year.
    pub fn edition(&mut self, edition: &str) -> &mut Self {
        self.cmd.arg("--edition");
        self.cmd.arg(edition);
        self
    }

    /// Specify the target triple, or a path to a custom target json spec file.
    pub fn target(&mut self, target: &str) -> &mut Self {
        self.cmd.arg(format!("--target={target}"));
        self
    }

    /// Specify the crate type.
    pub fn crate_type(&mut self, crate_type: &str) -> &mut Self {
        self.cmd.arg("--crate-type");
        self.cmd.arg(crate_type);
        self
    }

    /// Specify the crate name.
    pub fn crate_name<S: AsRef<OsStr>>(&mut self, name: S) -> &mut Self {
        self.cmd.arg("--crate-name");
        self.cmd.arg(name.as_ref());
        self
    }

    /// Add a directory to the library search path. It corresponds to the `-L`
    /// rustdoc option.
    pub fn library_search_path<P: AsRef<Path>>(&mut self, path: P) -> &mut Self {
        self.cmd.arg("-L");
        self.cmd.arg(path.as_ref());
        self
    }

    /// Specify the output format.
    pub fn output_format(&mut self, format: &str) -> &mut Self {
        self.cmd.arg("--output-format");
        self.cmd.arg(format);
        self
    }

    #[track_caller]
    pub fn run_fail_assert_exit_code(&mut self, code: i32) -> Output {
        let caller_location = std::panic::Location::caller();
        let caller_line_number = caller_location.line();

        let output = self.command_output();
        if output.status.code().unwrap() != code {
            handle_failed_output(&self.cmd, output, caller_line_number);
        }
        output
    }
}