#include "nocal/tui/unicode.hpp"

#include <iostream>
#include <string>
#include <string_view>

namespace {

int failures = 0;

void check(const bool condition, const std::string_view message)
{
    if (!condition) {
        ++failures;
        std::cerr << "FAIL: " << message << '\n';
    }
}

void test_decode_codepoint()
{
    // ASCII
    {
        const auto d = nocal::tui::decode_codepoint("A", 0);
        check(d.value == 0x41U && d.length == 1, "ASCII decode");
    }

    // Two-byte UTF-8 (U+00A9 ©)
    {
        const auto d = nocal::tui::decode_codepoint("\u00a9", 0);
        check(d.value == 0xa9U && d.length == 2, "2-byte decode");
    }

    // Three-byte UTF-8 (U+4E00 一)
    {
        const auto d = nocal::tui::decode_codepoint("\u4e00", 0);
        check(d.value == 0x4e00U && d.length == 3, "3-byte decode");
    }

    // Four-byte UTF-8 (U+1F600 😀)
    {
        const auto d = nocal::tui::decode_codepoint("\U0001f600", 0);
        check(d.value == 0x1f600U && d.length == 4, "4-byte decode");
    }

    // Invalid continuation byte → replacement character
    {
        const auto d = nocal::tui::decode_codepoint("\x80", 0);
        check(d.value == 0xfffdU && d.length == 1, "invalid byte yields replacement");
    }

    // Truncated sequence
    {
        const auto d = nocal::tui::decode_codepoint("\xc0", 0);
        check(d.value == 0xfffdU && d.length == 1, "truncated sequence yields replacement");
    }
}

void test_codepoint_width()
{
    // ASCII
    check(nocal::tui::codepoint_width(0x41U) == 1, "ASCII letter width 1");

    // Combining marks
    check(nocal::tui::codepoint_width(0x0300U) == 0, "combining grave accent width 0");
    check(nocal::tui::codepoint_width(0x036fU) == 0, "combining mark end width 0");
    check(nocal::tui::codepoint_width(0x1ab0U) == 0, "combining half mark start width 0");
    check(nocal::tui::codepoint_width(0x1affU) == 0, "combining half mark end width 0");
    check(nocal::tui::codepoint_width(0x1dc0U) == 0, "combining diacritical extended start width 0");
    check(nocal::tui::codepoint_width(0x1dffU) == 0, "combining diacritical extended end width 0");
    check(nocal::tui::codepoint_width(0x20d0U) == 0, "combining enclosing key symbols start width 0");
    check(nocal::tui::codepoint_width(0x20ffU) == 0, "combining enclosing key symbols end width 0");
    check(nocal::tui::codepoint_width(0xfe00U) == 0, "variation selector-1 width 0");
    check(nocal::tui::codepoint_width(0xfe0fU) == 0, "variation selector-16 width 0");
    check(nocal::tui::codepoint_width(0xfe20U) == 0, "combining ligature start width 0");
    check(nocal::tui::codepoint_width(0xfe2fU) == 0, "combining ligature end width 0");
    check(nocal::tui::codepoint_width(0x200dU) == 0, "ZWJ width 0");
    check(nocal::tui::codepoint_width(0x1f3fbU) == 2, "skin tone modifier standalone width 2");

    // Double-width CJK
    check(nocal::tui::codepoint_width(0x1100U) == 2, "Hangul Jamo start width 2");
    check(nocal::tui::codepoint_width(0x115fU) == 2, "Hangul Jamo end width 2");
    check(nocal::tui::codepoint_width(0x2329U) == 2, "left-pointing angle bracket width 2");
    check(nocal::tui::codepoint_width(0x232aU) == 2, "right-pointing angle bracket width 2");
    check(nocal::tui::codepoint_width(0x2e80U) == 2, "CJK radical start width 2");
    check(nocal::tui::codepoint_width(0xa4cfU) == 2, "Yi syllable end width 2");
    check(nocal::tui::codepoint_width(0xac00U) == 2, "Hangul syllable start width 2");
    check(nocal::tui::codepoint_width(0xd7a3U) == 2, "Hangul syllable end width 2");
    check(nocal::tui::codepoint_width(0xf900U) == 2, "CJK compat ideograph start width 2");
    check(nocal::tui::codepoint_width(0xfaffU) == 2, "CJK compat ideograph end width 2");
    check(nocal::tui::codepoint_width(0xfe10U) == 2, "vertical form start width 2");
    check(nocal::tui::codepoint_width(0xfe19U) == 2, "vertical form end width 2");
    check(nocal::tui::codepoint_width(0xfe30U) == 2, "CJK compat form start width 2");
    check(nocal::tui::codepoint_width(0xfe6fU) == 2, "CJK compat form end width 2");
    check(nocal::tui::codepoint_width(0xff00U) == 2, "fullwidth ASCII start width 2");
    check(nocal::tui::codepoint_width(0xff60U) == 2, "fullwidth ASCII end width 2");
    check(nocal::tui::codepoint_width(0xffe0U) == 2, "fullwidth symbol start width 2");
    check(nocal::tui::codepoint_width(0xffe6U) == 2, "fullwidth symbol end width 2");
    check(nocal::tui::codepoint_width(0x2600U) == 2, "misc symbol start width 2");
    check(nocal::tui::codepoint_width(0x27bfU) == 2, "misc symbol end width 2");
    check(nocal::tui::codepoint_width(0x1f300U) == 2, "misc symbol pictograph start width 2");
    check(nocal::tui::codepoint_width(0x1faffU) == 2, "misc symbol pictograph end width 2");
    check(nocal::tui::codepoint_width(0x20000U) == 2, "CJK ext B start width 2");
    check(nocal::tui::codepoint_width(0x3fffdU) == 2, "CJK ext B end width 2");

    // Regular CJK character (U+4E00)
    check(nocal::tui::codepoint_width(0x4e00U) == 2, "CJK ideograph width 2");
}

void test_display_width()
{
    using nocal::tui::display_width;

    // ASCII text: width equals byte count
    check(display_width("hello") == 5, "ASCII text width");
    check(display_width("") == 0, "empty string width");

    // CJK characters: each is width 2
    check(display_width("\u4e00") == 2, "single CJK width 2");
    check(display_width("\u4e00\u4e00") == 4, "two CJK width 4");
    check(display_width("a\u4e00b") == 4, "mixed ASCII+CJK width");

    // Combining marks: absorbed by base
    check(display_width("a\u0300") == 1, "letter+combining mark width 1");
    check(display_width("\u4e00\u0300") == 2, "CJK+combining mark width 2");

    // Emoji: width 2
    check(display_width("\U0001f600") == 2, "emoji width 2");
    check(display_width("\U0001f600\U0001f601") == 4, "two emoji width 4");

    // Skin tone modifiers: absorbed (e.g. 👋🏽)
    check(display_width("\U0001f44b\U0001f3fd") == 2, "emoji+skin tone width 2");

    // Regional indicator pairs: width 2 (e.g. 🇺🇸)
    check(display_width("\U0001f1fa\U0001f1f8") == 2, "US flag width 2");
}

void test_fit_text()
{
    using nocal::tui::fit_text;

    // Empty string
    check(fit_text("", 5) == "     ", "empty fit to 5");
    check(fit_text("", 0) == "", "empty fit to 0");
    check(fit_text("", -1) == "", "empty fit to negative");

    // Truncated to 0 width
    check(fit_text("hello", 0) == "", "fit to 0 width");
    check(fit_text("hello", -5) == "", "fit to negative width");

    // Text fits exactly
    check(fit_text("hi", 2) == "hi", "exact fit");
    check(fit_text("hi", 3) == "hi ", "pad to 3");
    check(fit_text("hi", 5) == "hi   ", "pad to 5");

    // Truncation with ellipsis
    check(fit_text("hello", 4) == "hel\u2026", "truncate with ellipsis width 4");
    check(fit_text("hello", 3) == "he\u2026", "truncate with ellipsis width 3");
    check(fit_text("hello", 2) == "h\u2026", "truncate with ellipsis width 2");
    check(fit_text("hello", 1) == "h", "truncate width 1 (no ellipsis)");

    // Truncation without ellipsis
    check(fit_text("hello", 3, false) == "hel", "truncate without ellipsis");

    // CJK truncation (no ellipsis)
    check(fit_text("\u4e00\u4e00\u4e00", 4, false) == "\u4e00\u4e00", "CJK truncate 2 chars no ellipsis");
    check(fit_text("\u4e00\u4e00\u4e00", 5, false) == "\u4e00\u4e00 ", "CJK fit 2 chars pad no ellipsis");

    // CJK with ellipsis
    check(fit_text("\u4e00\u4e00\u4e00", 5, true) == "\u4e00\u4e00\u2026", "CJK truncate with ellipsis");
}

void test_grapheme_clusters()
{
    using nocal::tui::display_width;
    using nocal::tui::fit_text;

    // ZWJ sequences (e.g. family emoji)
    // U+1F468 (man) + ZWJ + U+1F469 (woman) + ZWJ + U+1F467 (girl) + ZWJ + U+1F466 (boy)
    // This is a single grapheme cluster of width 2
    const std::string family = "\U0001f468\u200d\U0001f469\u200d\U0001f467\u200d\U0001f466";
    check(display_width(family) == 2, "ZWJ family emoji width 2");

    // Skin tone modifiers
    // Hand wave + skin tone
    const std::string wave = "\U0001f44b\U0001f3fd";
    check(display_width(wave) == 2, "wave+skin tone width 2");

    // Hair style modifiers
    // Person + red hair
    const std::string red_hair = "\U0001f9d1\U0001f9b0";
    check(display_width(red_hair) == 2, "person+red hair width 2");

    // fit_text with ZWJ: should not break inside cluster
    check(fit_text(family, 2) == family, "fit ZWJ at exact width");
    // When truncating to 1, the entire cluster should be dropped (no partial cluster)
    check(fit_text(family, 1) == " ", "fit ZWJ at width 1 drops cluster");
}

void test_regional_indicator_pairs()
{
    using nocal::tui::display_width;
    using nocal::tui::fit_text;

    // US flag
    const std::string us = "\U0001f1fa\U0001f1f8";
    check(display_width(us) == 2, "US flag width 2");

    // Japan flag
    const std::string jp = "\U0001f1ef\U0001f1f5";
    check(display_width(jp) == 2, "Japan flag width 2");

    // fit_text should not split a flag pair
    check(fit_text(us, 2) == us, "fit US flag at exact width");
    check(fit_text(us, 1) == " ", "fit US flag at width 1 drops pair");
}

void test_variation_selectors()
{
    using nocal::tui::display_width;

    // Emoji + variation selector
    check(display_width("\u2600") == 2, "sun without VS width 2");
    check(display_width("\u2600\ufe0f") == 2, "sun with VS16 width 2");

    // CJK + variation selector
    check(display_width("\u4e00") == 2, "CJK without VS width 2");
    check(display_width("\u4e00\ufe00") == 2, "CJK with VS1 width 2");
}

} // anonymous namespace

int main()
{
    test_decode_codepoint();
    test_codepoint_width();
    test_display_width();
    test_fit_text();
    test_grapheme_clusters();
    test_regional_indicator_pairs();
    test_variation_selectors();

    if (failures > 0) {
        std::cerr << "FAIL: " << failures << " test(s) failed\n";
        return 1;
    }
    std::cout << "OK: all unicode tests passed\n";
    return 0;
}