use std::{
    io::{stdin, stdout, Write},
    path::PathBuf,
    collections::HashSet,
};

use colored::*;
use kradical_parsing::radk;

pub fn search_by_radical(query: &mut String){
    let mut result: HashSet<_> = HashSet::new();
    let mut aux: HashSet<_> = HashSet::new();
    let path = get_radkfile_path();

    match radk::parse_file(path.unwrap()) { /* if it doesn't exist, just panic */
        Ok(radk_list) => {
            result.clear();

            /* First iteration: get the baseline for the results */
            let mut rad = query.chars().nth(1).unwrap();
            if rad == '*' || rad == '＊' {
                /* if search_by_strokes returned an error then something is very wrong */
                rad = search_by_strokes(query, &radk_list, 1).expect("Couldn't parse input");
            }

            for k in radk_list.iter() {
                if k.radical.glyph.contains(rad) {
                    for input in &k.kanji {
                        result.insert(input);
                    }
                    break;
                }
            }

            /* Iterate until you've exhausted user input: refine the baseline to get final output */
            for (i, mut rad) in query.clone().chars().skip(2).enumerate() {
                if rad == '*' || rad == '＊' {
                    /* if search_by_strokes returned an error then something is very wrong */
                    rad = search_by_strokes(query, &radk_list, i+2).expect("Couldn't parse input");
                }

                for k in radk_list.iter() {
                    if k.radical.glyph.contains(rad) {
                        for input in &k.kanji {
                            aux.insert(input);
                        }
                        result = &result & &aux;
                        aux.clear();
                        break;
                    }
                }
            }
            for r in result {
                print!("{r} ");
            }
            println!();
        }
        Err(_e) => eprintln!("Error while reading radkfile\nIf you don't have the radkfile, download it from \
        https://www.edrdg.org/krad/kradinf.html and place it in \"~/.local/share/\" on Linux or \"~\\AppData\\Local\\\" on Windows. \
        This file is needed to search radicals by strokes."),
    }
}

fn search_by_strokes(query: &mut String, radk_list: &[radk::Membership], n: usize) -> Result<char, std::io::Error> {

    let mut strokes = String::new();
    let mut radicals: Vec<char> = Vec::new();
    let rad;
    loop{
        print!("How many strokes does your radical have? ");
        stdout().flush()?;
        strokes.clear();
        if stdin().read_line(&mut strokes)? == 0{
            std::process::exit(0);
        }

        match strokes.trim().parse::<u8>() {
            Ok(strk) => {
                let mut i = 1;
                for k in radk_list.iter() {
                    if k.radical.strokes == strk {
                        print!("{}{} ", i, k.radical.glyph);
                        radicals.push(k.radical.glyph.chars().next().unwrap());
                        i += 1;
                    } else if k.radical.strokes > strk {
                        println!();
                        break;
                    }
                }
                loop {
                    print!("Choose the radical to use for your search: ");
                    stdout().flush()?;
                    strokes.clear();
                    if stdin().read_line(&mut strokes)? == 0{
                        std::process::exit(0);
                    }

                    match strokes.trim().parse::<usize>() {
                        Ok(strk) => {
                            if strk < 1 || strk > i-1 {
                                eprintln!("Couldn't parse input: number not in range");
                            } else {
                                rad = radicals.get(strk-1).unwrap();
                                /* UTF-8 is not fun */
                                let char_and_index = query.char_indices().nth(n).unwrap();
                                query.replace_range(char_and_index.0..
                                                    char_and_index.0 +
                                                    char_and_index.1.len_utf8(),
                                                    rad.to_string().as_str());
                                println!("{}", query.as_str().bright_black());
                                return Ok(*rad);
                            }
                        },
                        Err(e) => { eprintln!("{e}"); }
                    }
                }
            },
            Err(e) => { eprintln!("{e}") }
        }
    }
}

#[cfg(unix)]
fn get_radkfile_path() -> Option<PathBuf> {
    #[allow(deprecated)] /* obviously no windows problem here */
    std::env::home_dir()
        .map(|path| path.join(".local/share/radkfile"))
}

#[cfg(windows)]
/* Nicked this section straight from https://github.com/rust-lang/cargo/blob/master/crates/home/src/windows.rs */
extern "C" {
    fn wcslen(buf: *const u16) -> usize;
}
#[cfg(windows)]
fn get_radkfile_path() -> Option<PathBuf> {
    use std::ffi::OsString;
    use std::os::windows::ffi::OsStringExt;
    use windows_sys::Win32::Foundation::{MAX_PATH, S_OK};
    use windows_sys::Win32::UI::Shell::{SHGetFolderPathW, CSIDL_PROFILE};

    match env::var_os("USERPROFILE").filter(|s| !s.is_empty()).map(PathBuf::from) {
        Some(path) => {
            Some(path.join("Appdata\\Local\\radkfile"))
        },
        None => {
            unsafe {
                let mut path: Vec<u16> = Vec::with_capacity(MAX_PATH as usize);
                match SHGetFolderPathW(0, CSIDL_PROFILE as i32, 0, 0, path.as_mut_ptr()) {
                    S_OK => {
                        let len = wcslen(path.as_ptr());
                        path.set_len(len);
                        let s = OsString::from_wide(&path);
                        Some(PathBuf::from(s).join("Appdata\\Local\\radkfile"))
                    }
                    _ => None,
                }
            }
        }
    }
}