#include "key_mapper.h"

#include <algorithm>

namespace roro {

namespace {

constexpr char kArmed = '*';

bool isAccent(char c) { return c == '\'' || c == '`' || c == '^' || c == '"' || c == ',' || c == '~'; }

// Latin-1 code point for accent + base letter, or 0.
uint32_t composeLatin1(char accent, char base) {
    struct Entry {
        char accent;
        const char* bases;
        const uint32_t* codes;
    };
    static const uint32_t acute[] = {0xE1, 0xE9, 0xED, 0xF3, 0xFA, 0xFD, 0xC1, 0xC9, 0xCD, 0xD3, 0xDA, 0xDD};
    static const uint32_t grave[] = {0xE0, 0xE8, 0xEC, 0xF2, 0xF9, 0xC0, 0xC8, 0xCC, 0xD2, 0xD9};
    static const uint32_t circ[] = {0xE2, 0xEA, 0xEE, 0xF4, 0xFB, 0xC2, 0xCA, 0xCE, 0xD4, 0xDB};
    static const uint32_t diaer[] = {0xE4, 0xEB, 0xEF, 0xF6, 0xFC, 0xFF, 0xC4, 0xCB, 0xCF, 0xD6, 0xDC};
    static const uint32_t cedil[] = {0xE7, 0xC7};
    static const uint32_t tilde[] = {0xE3, 0xF1, 0xF5, 0xC3, 0xD1, 0xD5};
    static const Entry table[] = {
        {'\'', "aeiouyAEIOUY", acute}, {'`', "aeiouAEIOU", grave}, {'^', "aeiouAEIOU", circ},
        {'"', "aeiouyAEIOU", diaer},   {',', "cC", cedil},         {'~', "anoANO", tilde},
    };
    for (auto& e : table) {
        if (e.accent != accent) continue;
        for (int i = 0; e.bases[i]; i++)
            if (e.bases[i] == base) return e.codes[i];
    }
    return 0;
}

KeyEvent charEvent(uint32_t cp, const RawKeys& keys) {
    KeyEvent e = KeyEvent::character(cp);
    e.shift = keys.shift;
    e.ctrl = keys.ctrl;
    e.alt = keys.alt;
    return e;
}

}  // namespace

std::vector<KeyEvent> KeyMapper::update(const RawKeys& keys) {
    std::vector<KeyEvent> out;

    if (keys.opt && !previous_.opt && keys.chars.empty()) {
        compose_ = compose_ ? 0 : kArmed;  // a second opt cancels
    }
    if (keys.enter && !previous_.enter) out.push_back(KeyEvent::of(Key::Select));
    if (keys.del && !previous_.del) out.push_back(KeyEvent::of(Key::Delete));
    if (keys.tab && !previous_.tab) out.push_back(KeyEvent::of(Key::Tab));

    for (char c : keys.chars) {
        bool wasHeld = std::find(previous_.chars.begin(), previous_.chars.end(), c) != previous_.chars.end();
        if (!wasHeld) onChar(c, keys, out);
    }

    previous_ = keys;
    return out;
}

void KeyMapper::onChar(char c, const RawKeys& keys, std::vector<KeyEvent>& out) {
    // Holding opt while typing the accent is the same as pressing opt first.
    if (keys.opt && !compose_) compose_ = kArmed;

    if (compose_ == kArmed) {
        if (isAccent(c)) {
            compose_ = c;
            return;
        }
        compose_ = 0;  // not an accent: type it normally below
    } else if (compose_) {
        char accent = compose_;
        compose_ = 0;
        uint32_t composed = composeLatin1(accent, c);
        if (composed) {
            out.push_back(charEvent(composed, keys));
        } else {
            out.push_back(charEvent(static_cast<unsigned char>(accent), keys));
            out.push_back(charEvent(static_cast<unsigned char>(c), keys));
        }
        return;
    }

    if (keys.fn || !textEntry_) {
        switch (c) {
            case ';': out.push_back(KeyEvent::of(Key::Up)); return;
            case '.': out.push_back(KeyEvent::of(Key::Down)); return;
            case ',': out.push_back(KeyEvent::of(Key::Left)); return;
            case '/': out.push_back(KeyEvent::of(Key::Right)); return;
            case '`':
                if (keys.fn) {
                    out.push_back(KeyEvent::of(Key::Home));
                    return;
                }
                break;
            case 'h':
            case 'H':
                if (keys.fn) {  // Fn+h: help, while typing too
                    out.push_back(KeyEvent::of(Key::Help));
                    return;
                }
                break;
            case '?':
                if (!textEntry_ && !keys.fn) {  // ? alone, when it wouldn't be typed
                    out.push_back(KeyEvent::of(Key::Help));
                    return;
                }
                if (keys.fn) return;
                break;
            default:
                if (keys.fn) return;  // other Fn combos are unassigned
                break;
        }
    }
    if (c == '`') {
        out.push_back(KeyEvent::of(Key::Back));
        return;
    }
    out.push_back(charEvent(static_cast<unsigned char>(c), keys));
}

}  // namespace roro