//! String locale 三方法：toLocaleLowerCase / toLocaleUpperCase / localeCompare。
//!
//! toLocaleLowerCase 与 toLowerCase 同映射表，增量仅 Final Sigma 条件映射
//! （σ/ς 判定按原始单元序列、双向跳过 Mn/Cf 找最近可见字符）；
//! toLocaleUpperCase 与 toUpperCase 同表无条件映射；localeCompare 基本档 =
//! NFC 归一后 UTF-16 单元序比较，第二参缺省/undefined 落 "undefined" 串。

use std::cmp::Ordering;

use oxide_runtime_api::{NativeResult, VmHost};
use oxide_types::value::JsValue;

use crate::builtins_debug;

use super::common::try_string;
use super::{as_units, map_well_formed_segments, this_units};

// ── Mn/Cf 判定表 ─────────────────────────────────────────────────────────
//
// Final Sigma 条件映射的"不可见"判定：Mn（非连接修饰符号）与 Cf（格式字符）
// 全集范围表（UCD 快照，367 段，起点升序）。表取全集而非语料钉点，防语料
// 扩充翻车；仅当未来 Unicode 版本新增 Mn/Cf 码点且语料随之扩充时需重生成。

const MN_CF_RANGES: &[(u32, u32)] = &[
    (0xad, 0xad),
    (0x300, 0x36f),
    (0x483, 0x487),
    (0x591, 0x5bd),
    (0x5bf, 0x5bf),
    (0x5c1, 0x5c2),
    (0x5c4, 0x5c5),
    (0x5c7, 0x5c7),
    (0x600, 0x605),
    (0x610, 0x61a),
    (0x61c, 0x61c),
    (0x64b, 0x65f),
    (0x670, 0x670),
    (0x6d6, 0x6dc),
    (0x6dd, 0x6dd),
    (0x6df, 0x6e4),
    (0x6e7, 0x6e8),
    (0x6ea, 0x6ed),
    (0x70f, 0x70f),
    (0x711, 0x711),
    (0x730, 0x74a),
    (0x7a6, 0x7b0),
    (0x7eb, 0x7f3),
    (0x7fd, 0x7fd),
    (0x816, 0x819),
    (0x81b, 0x823),
    (0x825, 0x827),
    (0x829, 0x82d),
    (0x859, 0x85b),
    (0x890, 0x891),
    (0x898, 0x89f),
    (0x8ca, 0x8e1),
    (0x8e2, 0x8e2),
    (0x8e3, 0x902),
    (0x93a, 0x93a),
    (0x93c, 0x93c),
    (0x941, 0x948),
    (0x94d, 0x94d),
    (0x951, 0x957),
    (0x962, 0x963),
    (0x981, 0x981),
    (0x9bc, 0x9bc),
    (0x9c1, 0x9c4),
    (0x9cd, 0x9cd),
    (0x9e2, 0x9e3),
    (0x9fe, 0x9fe),
    (0xa01, 0xa02),
    (0xa3c, 0xa3c),
    (0xa41, 0xa42),
    (0xa47, 0xa48),
    (0xa4b, 0xa4d),
    (0xa51, 0xa51),
    (0xa70, 0xa71),
    (0xa75, 0xa75),
    (0xa81, 0xa82),
    (0xabc, 0xabc),
    (0xac1, 0xac5),
    (0xac7, 0xac8),
    (0xacd, 0xacd),
    (0xae2, 0xae3),
    (0xafa, 0xaff),
    (0xb01, 0xb01),
    (0xb3c, 0xb3c),
    (0xb3f, 0xb3f),
    (0xb41, 0xb44),
    (0xb4d, 0xb4d),
    (0xb55, 0xb56),
    (0xb62, 0xb63),
    (0xb82, 0xb82),
    (0xbc0, 0xbc0),
    (0xbcd, 0xbcd),
    (0xc00, 0xc00),
    (0xc04, 0xc04),
    (0xc3c, 0xc3c),
    (0xc3e, 0xc40),
    (0xc46, 0xc48),
    (0xc4a, 0xc4d),
    (0xc55, 0xc56),
    (0xc62, 0xc63),
    (0xc81, 0xc81),
    (0xcbc, 0xcbc),
    (0xcbf, 0xcbf),
    (0xcc6, 0xcc6),
    (0xccc, 0xccd),
    (0xce2, 0xce3),
    (0xd00, 0xd01),
    (0xd3b, 0xd3c),
    (0xd41, 0xd44),
    (0xd4d, 0xd4d),
    (0xd62, 0xd63),
    (0xd81, 0xd81),
    (0xdca, 0xdca),
    (0xdd2, 0xdd4),
    (0xdd6, 0xdd6),
    (0xe31, 0xe31),
    (0xe34, 0xe3a),
    (0xe47, 0xe4e),
    (0xeb1, 0xeb1),
    (0xeb4, 0xebc),
    (0xec8, 0xece),
    (0xf18, 0xf19),
    (0xf35, 0xf35),
    (0xf37, 0xf37),
    (0xf39, 0xf39),
    (0xf71, 0xf7e),
    (0xf80, 0xf84),
    (0xf86, 0xf87),
    (0xf8d, 0xf97),
    (0xf99, 0xfbc),
    (0xfc6, 0xfc6),
    (0x102d, 0x1030),
    (0x1032, 0x1037),
    (0x1039, 0x103a),
    (0x103d, 0x103e),
    (0x1058, 0x1059),
    (0x105e, 0x1060),
    (0x1071, 0x1074),
    (0x1082, 0x1082),
    (0x1085, 0x1086),
    (0x108d, 0x108d),
    (0x109d, 0x109d),
    (0x135d, 0x135f),
    (0x1712, 0x1714),
    (0x1732, 0x1733),
    (0x1752, 0x1753),
    (0x1772, 0x1773),
    (0x17b4, 0x17b5),
    (0x17b7, 0x17bd),
    (0x17c6, 0x17c6),
    (0x17c9, 0x17d3),
    (0x17dd, 0x17dd),
    (0x180b, 0x180d),
    (0x180e, 0x180e),
    (0x180f, 0x180f),
    (0x1885, 0x1886),
    (0x18a9, 0x18a9),
    (0x1920, 0x1922),
    (0x1927, 0x1928),
    (0x1932, 0x1932),
    (0x1939, 0x193b),
    (0x1a17, 0x1a18),
    (0x1a1b, 0x1a1b),
    (0x1a56, 0x1a56),
    (0x1a58, 0x1a5e),
    (0x1a60, 0x1a60),
    (0x1a62, 0x1a62),
    (0x1a65, 0x1a6c),
    (0x1a73, 0x1a7c),
    (0x1a7f, 0x1a7f),
    (0x1ab0, 0x1abd),
    (0x1abf, 0x1ace),
    (0x1b00, 0x1b03),
    (0x1b34, 0x1b34),
    (0x1b36, 0x1b3a),
    (0x1b3c, 0x1b3c),
    (0x1b42, 0x1b42),
    (0x1b6b, 0x1b73),
    (0x1b80, 0x1b81),
    (0x1ba2, 0x1ba5),
    (0x1ba8, 0x1ba9),
    (0x1bab, 0x1bad),
    (0x1be6, 0x1be6),
    (0x1be8, 0x1be9),
    (0x1bed, 0x1bed),
    (0x1bef, 0x1bf1),
    (0x1c2c, 0x1c33),
    (0x1c36, 0x1c37),
    (0x1cd0, 0x1cd2),
    (0x1cd4, 0x1ce0),
    (0x1ce2, 0x1ce8),
    (0x1ced, 0x1ced),
    (0x1cf4, 0x1cf4),
    (0x1cf8, 0x1cf9),
    (0x1dc0, 0x1dff),
    (0x200b, 0x200f),
    (0x202a, 0x202e),
    (0x2060, 0x2064),
    (0x2066, 0x206f),
    (0x20d0, 0x20dc),
    (0x20e1, 0x20e1),
    (0x20e5, 0x20f0),
    (0x2cef, 0x2cf1),
    (0x2d7f, 0x2d7f),
    (0x2de0, 0x2dff),
    (0x302a, 0x302d),
    (0x3099, 0x309a),
    (0xa66f, 0xa66f),
    (0xa674, 0xa67d),
    (0xa69e, 0xa69f),
    (0xa6f0, 0xa6f1),
    (0xa802, 0xa802),
    (0xa806, 0xa806),
    (0xa80b, 0xa80b),
    (0xa825, 0xa826),
    (0xa82c, 0xa82c),
    (0xa8c4, 0xa8c5),
    (0xa8e0, 0xa8f1),
    (0xa8ff, 0xa8ff),
    (0xa926, 0xa92d),
    (0xa947, 0xa951),
    (0xa980, 0xa982),
    (0xa9b3, 0xa9b3),
    (0xa9b6, 0xa9b9),
    (0xa9bc, 0xa9bd),
    (0xa9e5, 0xa9e5),
    (0xaa29, 0xaa2e),
    (0xaa31, 0xaa32),
    (0xaa35, 0xaa36),
    (0xaa43, 0xaa43),
    (0xaa4c, 0xaa4c),
    (0xaa7c, 0xaa7c),
    (0xaab0, 0xaab0),
    (0xaab2, 0xaab4),
    (0xaab7, 0xaab8),
    (0xaabe, 0xaabf),
    (0xaac1, 0xaac1),
    (0xaaec, 0xaaed),
    (0xaaf6, 0xaaf6),
    (0xabe5, 0xabe5),
    (0xabe8, 0xabe8),
    (0xabed, 0xabed),
    (0xfb1e, 0xfb1e),
    (0xfe00, 0xfe0f),
    (0xfe20, 0xfe2f),
    (0xfeff, 0xfeff),
    (0xfff9, 0xfffb),
    (0x101fd, 0x101fd),
    (0x102e0, 0x102e0),
    (0x10376, 0x1037a),
    (0x10a01, 0x10a03),
    (0x10a05, 0x10a06),
    (0x10a0c, 0x10a0f),
    (0x10a38, 0x10a3a),
    (0x10a3f, 0x10a3f),
    (0x10ae5, 0x10ae6),
    (0x10d24, 0x10d27),
    (0x10eab, 0x10eac),
    (0x10efd, 0x10eff),
    (0x10f46, 0x10f50),
    (0x10f82, 0x10f85),
    (0x11001, 0x11001),
    (0x11038, 0x11046),
    (0x11070, 0x11070),
    (0x11073, 0x11074),
    (0x1107f, 0x11081),
    (0x110b3, 0x110b6),
    (0x110b9, 0x110ba),
    (0x110bd, 0x110bd),
    (0x110c2, 0x110c2),
    (0x110cd, 0x110cd),
    (0x11100, 0x11102),
    (0x11127, 0x1112b),
    (0x1112d, 0x11134),
    (0x11173, 0x11173),
    (0x11180, 0x11181),
    (0x111b6, 0x111be),
    (0x111c9, 0x111cc),
    (0x111cf, 0x111cf),
    (0x1122f, 0x11231),
    (0x11234, 0x11234),
    (0x11236, 0x11237),
    (0x1123e, 0x1123e),
    (0x11241, 0x11241),
    (0x112df, 0x112df),
    (0x112e3, 0x112ea),
    (0x11300, 0x11301),
    (0x1133b, 0x1133c),
    (0x11340, 0x11340),
    (0x11366, 0x1136c),
    (0x11370, 0x11374),
    (0x11438, 0x1143f),
    (0x11442, 0x11444),
    (0x11446, 0x11446),
    (0x1145e, 0x1145e),
    (0x114b3, 0x114b8),
    (0x114ba, 0x114ba),
    (0x114bf, 0x114c0),
    (0x114c2, 0x114c3),
    (0x115b2, 0x115b5),
    (0x115bc, 0x115bd),
    (0x115bf, 0x115c0),
    (0x115dc, 0x115dd),
    (0x11633, 0x1163a),
    (0x1163d, 0x1163d),
    (0x1163f, 0x11640),
    (0x116ab, 0x116ab),
    (0x116ad, 0x116ad),
    (0x116b0, 0x116b5),
    (0x116b7, 0x116b7),
    (0x1171d, 0x1171f),
    (0x11722, 0x11725),
    (0x11727, 0x1172b),
    (0x1182f, 0x11837),
    (0x11839, 0x1183a),
    (0x1193b, 0x1193c),
    (0x1193e, 0x1193e),
    (0x11943, 0x11943),
    (0x119d4, 0x119d7),
    (0x119da, 0x119db),
    (0x119e0, 0x119e0),
    (0x11a01, 0x11a0a),
    (0x11a33, 0x11a38),
    (0x11a3b, 0x11a3e),
    (0x11a47, 0x11a47),
    (0x11a51, 0x11a56),
    (0x11a59, 0x11a5b),
    (0x11a8a, 0x11a96),
    (0x11a98, 0x11a99),
    (0x11c30, 0x11c36),
    (0x11c38, 0x11c3d),
    (0x11c3f, 0x11c3f),
    (0x11c92, 0x11ca7),
    (0x11caa, 0x11cb0),
    (0x11cb2, 0x11cb3),
    (0x11cb5, 0x11cb6),
    (0x11d31, 0x11d36),
    (0x11d3a, 0x11d3a),
    (0x11d3c, 0x11d3d),
    (0x11d3f, 0x11d45),
    (0x11d47, 0x11d47),
    (0x11d90, 0x11d91),
    (0x11d95, 0x11d95),
    (0x11d97, 0x11d97),
    (0x11ef3, 0x11ef4),
    (0x11f00, 0x11f01),
    (0x11f36, 0x11f3a),
    (0x11f40, 0x11f40),
    (0x11f42, 0x11f42),
    (0x13430, 0x1343f),
    (0x13440, 0x13440),
    (0x13447, 0x13455),
    (0x16af0, 0x16af4),
    (0x16b30, 0x16b36),
    (0x16f4f, 0x16f4f),
    (0x16f8f, 0x16f92),
    (0x16fe4, 0x16fe4),
    (0x1bc9d, 0x1bc9e),
    (0x1bca0, 0x1bca3),
    (0x1cf00, 0x1cf2d),
    (0x1cf30, 0x1cf46),
    (0x1d167, 0x1d169),
    (0x1d173, 0x1d17a),
    (0x1d17b, 0x1d182),
    (0x1d185, 0x1d18b),
    (0x1d1aa, 0x1d1ad),
    (0x1d242, 0x1d244),
    (0x1da00, 0x1da36),
    (0x1da3b, 0x1da6c),
    (0x1da75, 0x1da75),
    (0x1da84, 0x1da84),
    (0x1da9b, 0x1da9f),
    (0x1daa1, 0x1daaf),
    (0x1e000, 0x1e006),
    (0x1e008, 0x1e018),
    (0x1e01b, 0x1e021),
    (0x1e023, 0x1e024),
    (0x1e026, 0x1e02a),
    (0x1e08f, 0x1e08f),
    (0x1e130, 0x1e136),
    (0x1e2ae, 0x1e2ae),
    (0x1e2ec, 0x1e2ef),
    (0x1e4ec, 0x1e4ef),
    (0x1e8d0, 0x1e8d6),
    (0x1e944, 0x1e94a),
    (0xe0001, 0xe0001),
    (0xe0020, 0xe007f),
    (0xe0100, 0xe01ef),
];

/// 码点是否属 Mn/Cf（范围表二分判定，起点升序）。
fn is_mn_cf(cp: u32) -> bool {
    let idx = MN_CF_RANGES.partition_point(|&(lo, _)| lo <= cp);
    idx > 0 && cp <= MN_CF_RANGES[idx - 1].1
}

// ── Final Sigma 条件映射 ──────────────────────────────────────────────────

/// Final Sigma 条件小写映射：逐码点小写，其中 U+03A3（Σ）按条件规则取 σ/ς。
///
/// σ/ς 判定按原始单元序列（非变换后）：后向（索引升方向）跳过 Mn/Cf 单元
/// 存在可见字符 → σ；后向无且前向（索引降方向）跳过 Mn/Cf 存在可见字符 → ς；
/// 前后均无可见字符 → σ。孤立 surrogate 原样透传（与 toLowerCase 同口径）。
fn final_sigma_lower(units: &[u16]) -> Vec<u16> {
    let mut out = Vec::with_capacity(units.len());
    let mut i = 0;
    while i < units.len() {
        let u = units[i];
        if u == 0x03A3 {
            // 双向跳过 Mn/Cf 找最近可见字符（含行尾前的任意非 Mn/Cf 字符）。
            let mut j = i + 1;
            while j < units.len() && is_mn_cf(units[j] as u32) {
                j += 1;
            }
            let after_visible = j < units.len();
            let mut j = i;
            while j > 0 && is_mn_cf(units[j - 1] as u32) {
                j -= 1;
            }
            let before_visible = j > 0;
            out.push(if after_visible || !before_visible { 0x03C3 } else { 0x03C2 });
            i += 1;
            continue;
        }
        if (0xD800..=0xDBFF).contains(&u) && i + 1 < units.len() && (0xDC00..=0xDFFF).contains(&units[i + 1]) {
            // 代理对整体解码为码点小写后回写 UTF-16。
            let cp = (((u as u32) - 0xD800) << 10 | (units[i + 1] as u32 - 0xDC00)) + 0x10000;
            if let Some(c) = char::from_u32(cp) {
                out.extend(c.to_lowercase().collect::<String>().encode_utf16());
            }
            i += 2;
            continue;
        }
        if (0xD800..=0xDFFF).contains(&u) {
            out.push(u);
        } else if let Some(c) = char::from_u32(u as u32) {
            out.extend(c.to_lowercase().collect::<String>().encode_utf16());
        }
        i += 1;
    }
    out
}

// ── 三方法 ───────────────────────────────────────────────────────────────

/// `String.prototype.toLocaleLowerCase`：locale 无关小写（与 toLowerCase 同表，
/// 增量 Final Sigma 条件映射）。
pub fn string_to_locale_lower_case<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
    builtins_debug!("String.prototype.toLocaleLowerCase called with {} args", args.len());
    let s = try_string!(this_units(vm, args)).into_owned();
    let out = final_sigma_lower(&s);
    NativeResult::Ok(vm.new_string_units_owned(out))
}

/// `String.prototype.toLocaleUpperCase`：locale 无关大写（与 toUpperCase 同表，
/// 良形段映射，孤立 surrogate 单元原样保留）。
pub fn string_to_locale_upper_case<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
    builtins_debug!("String.prototype.toLocaleUpperCase called with {} args", args.len());
    let s = try_string!(this_units(vm, args));
    let out = map_well_formed_segments(&s, |seg| seg.to_uppercase());
    NativeResult::Ok(vm.new_string_units_owned(out))
}

/// `String.prototype.localeCompare(compareString)`：基本档比较——两侧 NFC 归一后
/// 按 UTF-16 单元序（良形文本下与码元序等价）返回 -1/0/1。
///
/// # 边界与前提
/// - 第二参缺省或 undefined 落 "undefined" 串（规范基本档允许）；其余非字符串经
///   完整 ToString，Symbol 抛 TypeError；this 的 null/undefined/symbol 经
///   this_units 抛 TypeError。
///
/// # 注意事项
/// - 非 NFC 等价但 UCA 可分的串按单元序判（如 "ö" vs "o"），属基本档固有边界。
pub fn string_locale_compare<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
    builtins_debug!("String.prototype.localeCompare called with {} args", args.len());
    use unicode_normalization::UnicodeNormalization;
    let a = try_string!(this_units(vm, args)).into_owned();
    let b = if args.len() > 1 && !vm.reg(args[1]).is_undefined() {
        try_string!(as_units(vm, vm.reg(args[1]))).into_owned()
    } else {
        "undefined".encode_utf16().collect()
    };
    // NFC 归一（良形段映射，孤立 surrogate 透传，与 normalize 同路径）。
    let a = map_well_formed_segments(&a, |seg| seg.nfc().collect());
    let b = map_well_formed_segments(&b, |seg| seg.nfc().collect());
    NativeResult::Ok(JsValue::int(match a.cmp(&b) {
        Ordering::Less => -1,
        Ordering::Equal => 0,
        Ordering::Greater => 1,
    }))
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn mn_cf_table_corpus_points() {
        // 语料钉死码点：Cf/Mn 在表、Lu 不属表。
        assert!(is_mn_cf(0x00AD));
        assert!(is_mn_cf(0x0345));
        assert!(is_mn_cf(0x180E));
        assert!(is_mn_cf(0x1D242));
        assert!(!is_mn_cf(0x1D4A2));
        assert!(!is_mn_cf(0x0041));
    }

    #[test]
    fn final_sigma_conditional_mapping() {
        // （输入单元, 期望输出）：单枚/前后可见/行首行尾 Mn/Cf 环绕。
        let cases: &[(&[u16], &[u16])] = &[
            (&[0x03A3], &[0x03C3]),
            (&[0x41, 0x03A3], &[0x61, 0x03C2]),
            (&[0xD835, 0xDCA2, 0x03A3], &[0xD835, 0xDCA2, 0x03C2]),
            (&[0x0345, 0x03A3], &[0x0345, 0x03C3]),
            (&[0x41, 0x03A3, 0x2E], &[0x61, 0x03C3, 0x2E]),
            (&[0x41, 0x03A3, 0x0345], &[0x61, 0x03C2, 0x0345]),
            (&[0x41, 0x03A3, 0x180E], &[0x61, 0x03C2, 0x180E]),
            (&[0x41, 0x03A3, 0x180E, 0x42], &[0x61, 0x03C3, 0x180E, 0x62]),
        ];
        for (input, want) in cases {
            assert_eq!(&final_sigma_lower(input), want);
        }
    }
}