/*! Testing functionality */

use crate::data::parsing::Layout;
use crate::logging;
use xkbcommon::xkb;


pub struct CountAndPrint(u32);

impl logging::Handler for CountAndPrint {
    fn handle(&mut self, level: logging::Level, warning: &str) {
        use crate::logging::Level::*;
        match level {
            Panic | Bug | Error | Warning | Surprise => {
                self.0 += 1;
            },
            _ => {}
        }
        logging::Print{}.handle(level, warning)
    }
}

impl CountAndPrint {
    fn new() -> CountAndPrint {
        CountAndPrint(0)
    }
}

pub fn check_builtin_layout(name: &str, missing_return: bool) {
    check_layout(
        Layout::from_resource(name).expect("Invalid layout data"),
        missing_return,
    )
}

pub fn check_layout_file(path: &str) {
    check_layout(
        Layout::from_file(path.into()).expect("Invalid layout file"),
        false,
    )
}

fn check_sym_in_keymap(state: &xkb::State, sym_name: &str) -> bool {
    let sym = xkb::keysym_from_name(sym_name, xkb::KEYSYM_NO_FLAGS);
    if sym.raw() == xkb::keysyms::KEY_NoSymbol {
        panic!("Entered invalid keysym: {}", sym_name);
    }
    let map = state.get_keymap();
    let range = map.min_keycode().raw()..=map.max_keycode().raw();
    range.flat_map(|code| state.key_get_syms(code.into()))
        .find(|s| **s == sym)
        .is_some()
}

fn check_sym_presence(
    states: &[xkb::State],
    sym_name: &str,
    handler: &mut dyn logging::Handler,
) {
    let found = states.iter()
        .position(|state| {
            check_sym_in_keymap(&state, sym_name)
        });

    if let None = found {
        handler.handle(
            logging::Level::Surprise,
            &format!("There's no way to input the keysym {} on this layout", sym_name),
        )
    }
}

fn check_layout(layout: Layout, allow_missing_return: bool) {
    let handler = CountAndPrint::new();
    let (layout, mut handler) = layout.build(handler);

    if handler.0 > 0 {
        println!("{} problems while parsing layout", handler.0)
    }

    let layout = layout.expect("layout broken");
    
    let xkb_states: Vec<xkb::State> = layout.keymaps.iter()
        .map(|keymap_str| {
            let context = xkb::Context::new(xkb::CONTEXT_NO_FLAGS);
            let keymap_str = keymap_str
                .clone()
                .into_string().expect("Failed to decode keymap string");
            let keymap = xkb::Keymap::new_from_string(
                &context,
                keymap_str.clone(),
                xkb::KEYMAP_FORMAT_TEXT_V1,
                xkb::KEYMAP_COMPILE_NO_FLAGS,
            ).expect("Failed to create keymap");
            xkb::State::new(&keymap)
        })
        .collect();

    check_sym_presence(&xkb_states, "BackSpace", &mut handler);
    let mut printer = logging::Print;
    check_sym_presence(
        &xkb_states,
        "Return",
        if allow_missing_return { &mut printer }
        else { &mut handler },
    );

    // "Press" each button with keysyms
    for (_pos, view) in layout.views.values() {
        for (_y, row) in view.get_rows() {
            for (_x, button) in row.get_buttons() {
                for keycode in &button.keycodes {
                    match xkb_states[keycode.keymap_idx].key_get_one_sym(keycode.code.into()).raw() {
                        xkb::keysyms::KEY_NoSymbol => {
                            eprintln!(
                                "keymap {}: {}",
                                keycode.keymap_idx,
                                layout.keymaps[keycode.keymap_idx].to_str().unwrap(),
                            );
                            panic!(
                                "Keysym for code {:?} on key {} ({:?}) can't be resolved",
                                keycode,
                                button.name.to_string_lossy(),
                                button.name,
                            );
                        },
                        _ => {},
                    }
                }
            }
        }
    }

    if handler.0 > 0 {
        panic!("Layout contains mistakes");
    }
}