use std::{fs, path};

use color_eyre::{eyre::eyre, eyre::WrapErr};

pub fn path_or_err<P>(path: P) -> eyre::Result<path::PathBuf>
where
    P: AsRef<path::Path>,
{
    let path_as_buf = path::PathBuf::from(path.as_ref());

    if !path_as_buf.exists() {
        return Err(eyre!("Path not found or permission denied"))
            .wrap_err(format!("'{}' is not a path", path_as_buf.to_string_lossy()));
    }

    Ok(path_as_buf)
}

pub fn file_or_err<P>(path: P) -> eyre::Result<path::PathBuf>
where
    P: AsRef<path::Path>,
{
    let path_as_buf = path::PathBuf::from(path.as_ref());

    if !path_as_buf.is_file() {
        return Err(eyre!("File not found or permission denied"))
            .wrap_err(format!("'{}' is not a file", path_as_buf.to_string_lossy()));
    }

    Ok(path_as_buf)
}

pub fn dir_or_err<P>(path: P) -> eyre::Result<path::PathBuf>
where
    P: AsRef<path::Path>,
{
    let path_as_buf = path::PathBuf::from(path.as_ref());
    let meta = fs::metadata(path.as_ref()).wrap_err(format!(
        "'{}' is not a directory",
        path_as_buf.to_string_lossy()
    ))?;

    if !meta.is_dir() {
        return Err(eyre!("Directory not found")).wrap_err(format!(
            "'{}' is not a directory",
            path_as_buf.to_string_lossy()
        ));
    }

    Ok(path_as_buf)
}

pub fn file_with_name<P>(path: P, name: &str) -> eyre::Result<path::PathBuf>
where
    P: AsRef<path::Path>,
{
    let buf = file_or_err(path.as_ref())?;
    let name_str = buf.to_string_lossy();

    let file_name = path
        .as_ref()
        .file_name()
        .and_then(std::ffi::OsStr::to_str)
        .ok_or(eyre!(format!(
            "Expected file with name '{name}', got '{name_str}'"
        )))?;

    if file_name.to_lowercase() != name.to_lowercase() {
        return Err(eyre!(format!(
            "Expected file with name '{name}', got '{name_str}'"
        )));
    }
    Ok(buf)
}

pub fn file_with_ext<P>(path: P, ext: &str, strict: bool) -> eyre::Result<path::PathBuf>
where
    P: AsRef<path::Path>,
{
    let buf = file_or_err(path.as_ref())?;
    let name = buf.to_string_lossy();

    let file_ext = path
        .as_ref()
        .extension()
        .and_then(std::ffi::OsStr::to_str)
        .ok_or(eyre!(format!(
            "Expected file with extension '{ext}', got file '{name}'"
        )))?;

    let ext_minus = match ext.chars().next() {
        Some(c) if c == '.' && !strict => &ext[1..],
        _ => ext,
    };

    // if ext.starts_with(".") {
    //     &ext[1..]
    // }

    if ext_minus.to_lowercase() != file_ext.to_lowercase() {
        return Err(eyre!(format!(
            "Expected file extension '{ext_minus}', got '{file_ext}'"
        )));
    }
    Ok(buf)
}

pub fn file_with_name_or_ext<P>(path: P, name_or_ext: &str) -> eyre::Result<path::PathBuf>
where
    P: AsRef<path::Path>,
{
    let buf = file_or_err(path.as_ref())?;

    let f_for_name = file_with_name(path.as_ref(), name_or_ext);
    let f_for_ext = file_with_ext(path.as_ref(), name_or_ext, false);

    match f_for_name {
        Ok(path) => Ok(path),
        Err(_) => match f_for_ext {
            Ok(path) => Ok(path),
            Err(_) => Err(eyre!(format!(
                "Expected file with name or extension '{}', got '{}'",
                name_or_ext,
                buf.to_string_lossy()
            ))),
        },
    }
}

pub fn filename_or_exists<P>(path: P, root: Option<P>) -> eyre::Result<path::PathBuf>
where
    P: AsRef<path::Path>,
{
    if path.as_ref().is_absolute() && !path.as_ref().exists() {
        return Err(eyre::eyre!(format!(
            "'{}' does not exist",
            path.as_ref().to_string_lossy()
        )));
    }

    // this is one way to find out of if the specified path is only a file- or directory name
    // for paths that are provided as pure filenames, no checks are performed since they can be
    // part of search paths (e.g., for command names)
    let is_file = path
        .as_ref()
        .file_name()
        .and_then(|file_name| (path.as_ref().as_os_str() == file_name).then_some(true))
        .is_some();

    if is_file {
        return Ok(path.as_ref().to_path_buf());
    }

    if path.as_ref().is_relative() {
        let full_path = match root {
            None => path.as_ref().to_path_buf(),
            Some(root) => {
                let mut full_path = root.as_ref().to_path_buf();
                full_path.push(path.as_ref());
                full_path
            }
        };
        if !full_path.exists() {
            return Err(eyre::eyre!(format!(
                "'{}' does not exist",
                path.as_ref().to_string_lossy()
            )));
        }
        return Ok(full_path);
    }

    Ok(path.as_ref().to_path_buf())
}

pub fn filename_or_exists_with_ext<P>(
    path: P,
    root: Option<P>,
    ext: Option<&str>,
) -> eyre::Result<path::PathBuf>
where
    P: AsRef<path::Path>,
{
    let path_buf = path.as_ref().to_path_buf();
    let root_buf = root.map(|p| p.as_ref().to_path_buf());

    let mut checks = vec![filename_or_exists(path_buf, root_buf.clone())];

    // allow to omit the extension, e.g., .exe for Windows
    if let Some(ext) = ext {
        let mut try_ext = path.as_ref().to_path_buf();
        try_ext.set_extension(ext);

        checks.push(filename_or_exists(try_ext, root_buf));
    }

    // println!("commands to check: {:?}", checks);

    let has_path = checks.iter().find(|result| result.is_ok());
    if let Some(cmd) = has_path {
        return Ok(cmd.as_ref().unwrap().as_path().to_path_buf());
    }

    Err(checks.remove(0).unwrap_err())
}

pub fn executable_or_exists<P>(path: P, root: Option<P>) -> eyre::Result<path::PathBuf>
where
    P: AsRef<path::Path>,
{
    let ext = if cfg!(windows) { Some("exe") } else { None };
    filename_or_exists_with_ext(path, root, ext)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_path() {
        let path = path::Path::new("some/path/to/.clang-format");
        let file_name = path.file_name().and_then(std::ffi::OsStr::to_str).unwrap();

        assert_eq!(".clang-format", file_name.to_lowercase());
    }
}