#include "spt.h"

#include "m2_tokvec.h" // read_file

#include <cctype>
#include <cstdint>
#include <cstring>

namespace fmt {

namespace {

bool ends_with_ci(const std::string& s, const char* suf) {
    size_t n = std::strlen(suf);
    if (s.size() < n) return false;
    for (size_t i = 0; i < n; ++i)
        if (std::tolower((unsigned char)s[s.size() - n + i]) != std::tolower((unsigned char)suf[i]))
            return false;
    return true;
}

std::string token_ci(const std::string& bytes, const char* needle) {
    const size_t n = std::strlen(needle);
    if (n == 0 || bytes.size() < n) return "";
    for (size_t i = 0; i + n <= bytes.size(); ++i) {
        bool match = true;
        for (size_t j = 0; j < n; ++j) {
            if (std::tolower((unsigned char)bytes[i + j]) !=
                    std::tolower((unsigned char)needle[j])) {
                match = false;
                break;
            }
        }
        if (!match) continue;
        size_t e = i + n;
        while (e < bytes.size()) {
            const unsigned char c = (unsigned char)bytes[e];
            if (!(std::isalnum(c) || c == '_' || c == '-')) break;
            ++e;
        }
        return bytes.substr(i, e - i);
    }
    return "";
}

std::string as_dds(std::string s) {
    if (s.empty()) return s;
    const size_t dot = s.find_last_of('.');
    if (dot != std::string::npos) s.resize(dot);
    return s + ".dds";
}

} // namespace

bool sniff_spt(const std::string& b, SptInfo& out) {
    out = SptInfo{};
    if (b.size() < 20) return false;

    std::memcpy(&out.header_dword, b.data(), 4);
    uint32_t maglen = 0;
    std::memcpy(&maglen, b.data() + 4, 4);
    if (maglen >= 4 && maglen <= 32 && 8 + maglen <= b.size()) {
        out.magic.assign(b.data() + 8, b.data() + 8 + maglen);
        // 去掉可能的尾随 NUL
        while (!out.magic.empty() && out.magic.back() == '\0') out.magic.pop_back();
    }
    out.ok = out.magic.rfind("__IdvSpt", 0) == 0;

    // 扫描可打印 ASCII 段，收 .tga / .dds 结尾的
    std::string cur;
    auto flush = [&] {
        if (cur.size() >= 5 && (ends_with_ci(cur, ".tga") || ends_with_ci(cur, ".dds"))) {
            // 只留文件名基础部分之后的路径（原样）
            out.texture_refs.push_back(cur);
        }
        cur.clear();
    };
    for (unsigned char c : b) {
        if (c >= 0x20 && c < 0x7F) {
            cur += (char)c;
        } else {
            flush();
        }
    }
    flush();

    // 这两个名字在真实 v2 .spt 中常紧跟二进制标记，不会由上面的
    // "字符串必须正好以扩展名结尾" 规则捕获。
    out.composite_texture = as_dds(token_ci(b, "CompositeMap"));
    out.self_shadow_texture = as_dds(token_ci(b, "CompositeShadowMap"));
    return out.ok;
}

bool sniff_spt_file(const std::string& path, SptInfo& out) {
    std::string b;
    if (!read_file(path, b)) return false;
    return sniff_spt(b, out);
}

} // namespace fmt