#include "http_head.h"

#include <algorithm>
#include <cctype>
#include <cstdlib>

namespace roro::release {

namespace {
std::string lower(std::string s) {
    for (char& c : s) c = static_cast<char>(std::tolower(static_cast<unsigned char>(c)));
    return s;
}
}  // namespace

size_t HttpHeadParser::feed(const char* data, size_t len) {
    size_t used = 0;
    while (used < len && !complete_ && !failed_) {
        char c = data[used++];
        total_++;
        if (total_ > kMaxBytes) {
            failed_ = true;
            break;
        }
        if (c == '\n') {
            if (!line_.empty() && line_.back() == '\r') line_.pop_back();
            line();
            line_.clear();
        } else {
            line_ += c;
        }
    }
    return used;
}

void HttpHeadParser::line() {
    if (first_) {  // "HTTP/1.1 200 OK"
        first_ = false;
        if (line_.compare(0, 5, "HTTP/") != 0) {
            failed_ = true;
            return;
        }
        size_t space = line_.find(' ');
        head_.status = space == std::string::npos ? 0 : std::atoi(line_.c_str() + space + 1);
        if (head_.status < 100 || head_.status > 599) failed_ = true;
        return;
    }
    if (line_.empty()) {
        complete_ = true;
        return;
    }
    size_t colon = line_.find(':');
    if (colon == std::string::npos) return;  // not a header: ignored
    std::string name = lower(line_.substr(0, colon));
    size_t from = line_.find_first_not_of(" \t", colon + 1);
    std::string value = from == std::string::npos ? "" : line_.substr(from);
    if (name == "content-length") head_.contentLength = std::atol(value.c_str());
    else if (name == "transfer-encoding") head_.chunked = lower(value).find("chunked") != std::string::npos;
    else if (name == "location") head_.location = value;
    else if (name == "content-type") head_.contentType = value;
}

size_t ChunkedDecoder::decode(const uint8_t* in, size_t len, uint8_t* out) {
    size_t written = 0;
    for (size_t i = 0; i < len && !failed_ && state_ != State::Done; i++) {
        uint8_t c = in[i];
        switch (state_) {
            case State::Size: {
                int digit = c >= '0' && c <= '9' ? c - '0' : c >= 'a' && c <= 'f' ? c - 'a' + 10 : c >= 'A' && c <= 'F' ? c - 'A' + 10 : -1;
                if (digit >= 0) {
                    if (remaining_ > (SIZE_MAX >> 5)) failed_ = true;
                    remaining_ = remaining_ * 16 + digit;
                    anyDigit_ = true;
                } else if (c == ';' && anyDigit_) {
                    state_ = State::Extension;
                } else if (c == '\r' && anyDigit_) {
                    state_ = State::SizeLf;
                } else {
                    failed_ = true;
                }
                break;
            }
            case State::Extension:
                if (c == '\r') state_ = State::SizeLf;
                break;
            case State::SizeLf:
                if (c != '\n') {
                    failed_ = true;
                } else if (remaining_ == 0) {
                    state_ = State::Trailer;
                    trailerLine_ = 0;
                } else {
                    state_ = State::Data;
                }
                break;
            case State::Data: {
                size_t take = std::min(remaining_, len - i);
                for (size_t k = 0; k < take; k++) out[written + k] = in[i + k];
                written += take;
                remaining_ -= take;
                i += take - 1;
                if (remaining_ == 0) state_ = State::DataCr;
                break;
            }
            case State::DataCr:
                if (c != '\r') failed_ = true;
                else state_ = State::DataLf;
                break;
            case State::DataLf:
                if (c != '\n') {
                    failed_ = true;
                } else {
                    state_ = State::Size;
                    anyDigit_ = false;
                }
                break;
            case State::Trailer:  // header lines after the last chunk, until an empty one
                if (c == '\n') {
                    if (trailerLine_ == 0) state_ = State::Done;
                    trailerLine_ = 0;
                } else if (c != '\r') {
                    trailerLine_++;
                }
                break;
            case State::Done: break;
        }
    }
    return written;
}

Url parseUrl(const std::string& url) {
    Url u;
    size_t scheme = url.find("://");
    if (scheme == std::string::npos) return u;
    std::string s = lower(url.substr(0, scheme));
    if (s != "http" && s != "https") return u;
    u.https = s == "https";
    size_t hostStart = scheme + 3, pathStart = url.find('/', hostStart);
    std::string authority = url.substr(hostStart, pathStart == std::string::npos ? std::string::npos : pathStart - hostStart);
    u.path = pathStart == std::string::npos ? "/" : url.substr(pathStart);
    if (authority.empty() || authority.find('@') != std::string::npos) return u;  // no credentials in a URL
    size_t colon = authority.rfind(':');
    u.port = u.https ? 443 : 80;
    if (colon != std::string::npos) {
        u.port = std::atoi(authority.c_str() + colon + 1);
        authority.resize(colon);
        if (u.port <= 0 || u.port > 65535) return u;
    }
    for (unsigned char c : authority)
        if (!(std::isalnum(c) || c == '.' || c == '-')) return u;
    for (unsigned char c : u.path)
        if (c <= ' ' || c == 0x7F) return u;
    u.host = lower(authority);
    u.ok = !u.host.empty();
    return u;
}

}  // namespace roro::release