#![warn(clippy::str_split_at_newline)]
#![allow(clippy::needless_lifetimes)]

use core::str::Split;
use std::ops::Deref;

struct NotStr<'a> {
    s: &'a str,
}

impl<'a> NotStr<'a> {
    fn trim(&'a self) -> &'a str {
        self.s
    }
}

struct DerefsIntoNotStr<'a> {
    not_str: &'a NotStr<'a>,
}

impl<'a> Deref for DerefsIntoNotStr<'a> {
    type Target = NotStr<'a>;

    fn deref(&self) -> &Self::Target {
        self.not_str
    }
}

struct DerefsIntoStr<'a> {
    s: &'a str,
}

impl<'a> Deref for DerefsIntoStr<'a> {
    type Target = str;

    fn deref(&self) -> &Self::Target {
        self.s
    }
}

macro_rules! trim_split {
    ( $x:expr, $y:expr ) => {
        $x.trim().split($y);
    };
}

macro_rules! make_str {
    ( $x: expr ) => {
        format!("x={}", $x)
    };
}

fn main() {
    let s1 = "hello\nworld\n";
    let s2 = s1.to_owned();

    // CASES THAT SHOULD EMIT A LINT

    // Splitting a `str` variable at "\n" or "\r\n" after trimming should warn
    let _ = s1.trim().split('\n');
    //~^ str_split_at_newline
    #[allow(clippy::single_char_pattern)]
    let _ = s1.trim().split("\n");
    //~^ str_split_at_newline
    let _ = s1.trim().split("\r\n");
    //~^ str_split_at_newline

    // Splitting a `String` variable at "\n" or "\r\n" after trimming should warn
    let _ = s2.trim().split('\n');
    //~^ str_split_at_newline
    #[allow(clippy::single_char_pattern)]
    let _ = s2.trim().split("\n");
    //~^ str_split_at_newline
    let _ = s2.trim().split("\r\n");
    //~^ str_split_at_newline

    // Splitting a variable that derefs into `str` at "\n" or "\r\n" after trimming should warn.
    let s3 = DerefsIntoStr { s: s1 };
    let _ = s3.trim().split('\n');
    //~^ str_split_at_newline
    #[allow(clippy::single_char_pattern)]
    let _ = s3.trim().split("\n");
    //~^ str_split_at_newline
    let _ = s3.trim().split("\r\n");
    //~^ str_split_at_newline

    // If the `&str` is generated by a macro then the macro should not be expanded in the suggested fix.
    let _ = make_str!(s1).trim().split('\n');
    //~^ str_split_at_newline

    // CASES THAT SHOULD NOT EMIT A LINT

    // Splitting a `str` constant at "\n" or "\r\n" after trimming should not warn
    let _ = "hello\nworld\n".trim().split('\n');
    #[allow(clippy::single_char_pattern)]
    let _ = "hello\nworld\n".trim().split("\n");
    let _ = "hello\nworld\n".trim().split("\r\n");

    // Splitting a `str` variable at "\n" or "\r\n" without trimming should not warn, since it is not
    // equivalent
    let _ = s1.split('\n');
    #[allow(clippy::single_char_pattern)]
    let _ = s1.split("\n");
    let _ = s1.split("\r\n");

    // Splitting a `String` variable at "\n" or "\r\n" without trimming should not warn.
    let _ = s2.split('\n');
    #[allow(clippy::single_char_pattern)]
    let _ = s2.split("\n");

    // Splitting a variable that derefs into `str` at "\n" or "\r\n" without trimming should not warn.
    let _ = s3.split('\n');
    #[allow(clippy::single_char_pattern)]
    let _ = s3.split("\n");
    let _ = s3.split("\r\n");
    let _ = s2.split("\r\n");

    // Splitting a `str` variable at other separators should not warn
    let _ = s1.trim().split('\r');
    #[allow(clippy::single_char_pattern)]
    let _ = s1.trim().split("\r");
    let _ = s1.trim().split("\n\r");
    let _ = s1.trim().split("\r \n");

    // Splitting a `String` variable at other separators should not warn
    let _ = s2.trim().split('\r');
    #[allow(clippy::single_char_pattern)]
    let _ = s2.trim().split("\r");
    let _ = s2.trim().split("\n\r");

    // Splitting a variable that derefs into `str` at other separators should not warn
    let _ = s3.trim().split('\r');
    #[allow(clippy::single_char_pattern)]
    let _ = s3.trim().split("\r");
    let _ = s3.trim().split("\n\r");
    let _ = s3.trim().split("\r \n");
    let _ = s2.trim().split("\r \n");

    // Using `trim` and `split` on other types should not warn
    let not_str = NotStr { s: s1 };
    let _ = not_str.trim().split('\n');
    #[allow(clippy::single_char_pattern)]
    let _ = not_str.trim().split("\n");
    let _ = not_str.trim().split("\r\n");
    let derefs_into_not_str = DerefsIntoNotStr { not_str: &not_str };
    let _ = derefs_into_not_str.trim().split('\n');
    #[allow(clippy::single_char_pattern)]
    let _ = derefs_into_not_str.trim().split("\n");
    let _ = derefs_into_not_str.trim().split("\r\n");

    // Code generated by macros should not create a warning
    trim_split!(s1, "\r\n");
    trim_split!("hello\nworld\n", "\r\n");
    trim_split!(s2, "\r\n");
    trim_split!(s3, "\r\n");
}