#include "network/schedule_cache.h"
#include "network/json.h"

#include <cstdio>
#include <cstdlib>
#include <fstream>
#include <pwd.h>
#include <sstream>
#include <sys/stat.h>
#include <unistd.h>

namespace radiantwave::sync::schedule_cache {

namespace {

std::string homeDir() {
    const char* home = std::getenv("HOME");
    if (!home) {
        struct passwd* pw = getpwuid(getuid());
        if (pw) home = pw->pw_dir;
    }
    return home ? std::string(home) : std::string("/tmp");
}

void ensureDir(const std::string& dir) {
    // Create the directory and any missing parents (e.g. ~/.local/radiantwave
    // when ~/.local does not exist yet).
    std::string path;
    for (size_t i = 0; i < dir.size(); ++i) {
        path += dir[i];
        if (dir[i] == '/' || i == dir.size() - 1) {
            if (path.size() > 1) {
                mkdir(path.c_str(), 0755);
            }
        }
    }
}

// Minimal JSON string escaping for the cache writer.
std::string escape(const std::string& in) {
    std::string out;
    out.reserve(in.size() + 2);
    for (char c : in) {
        switch (c) {
        case '"': out += "\\\""; break;
        case '\\': out += "\\\\"; break;
        case '\n': out += "\\n"; break;
        case '\r': out += "\\r"; break;
        case '\t': out += "\\t"; break;
        default: out += c;
        }
    }
    return out;
}

std::string blockJson(const api::TargetBlock& block, bool includeDay) {
    std::ostringstream os;
    os << "{\"id\":\"" << escape(block.id) << "\"";
    if (includeDay) {
        os << ",\"day\":\"" << escape(block.day) << "\"";
    }
    os << ",\"startMinutes\":" << block.start_minutes
       << ",\"endMinutes\":" << block.end_minutes
       << ",\"overnight\":" << (block.overnight ? "true" : "false")
       << ",\"durationMinutes\":" << block.duration_minutes
       << ",\"dynamicAudio\":" << (block.dynamic_audio ? "true" : "false")
       << ",\"proclamationIds\":[";
    for (size_t i = 0; i < block.proclamation_ids.size(); ++i) {
        if (i > 0) os << ",";
        os << "\"" << escape(block.proclamation_ids[i]) << "\"";
    }
    os << "]}";
    return os.str();
}

std::string serialize(const api::SchedulePayload& payload, const std::string& etag) {
    std::ostringstream os;
    os << "{\"version\":\"" << escape(payload.version)
       << "\",\"type\":\"" << escape(payload.type)
       << "\",\"etag\":\"" << escape(etag)
       << "\",\"daily\":[";
    for (size_t i = 0; i < payload.daily.size(); ++i) {
        if (i > 0) os << ",";
        os << blockJson(payload.daily[i], false);
    }
    os << "],\"weekly\":[";
    for (size_t i = 0; i < payload.weekly.size(); ++i) {
        if (i > 0) os << ",";
        os << blockJson(payload.weekly[i], true);
    }
    os << "]}";
    return os.str();
}

} // namespace

std::string cachePath() {
    return homeDir() + "/.local/radiantwave/schedule_cache.json";
}

bool write(const api::SchedulePayload& payload, const std::string& etag) {
    const std::string dir = homeDir() + "/.local/radiantwave";
    ensureDir(dir);

    const std::string path = cachePath();
    const std::string tmp = path + ".tmp";

    {
        std::ofstream out(tmp, std::ios::binary | std::ios::trunc);
        if (!out.is_open()) return false;
        out << serialize(payload, etag);
        out.flush();
        if (!out.good()) {
            out.close();
            std::remove(tmp.c_str());
            return false;
        }
    }

    // Atomic replace: a same-filesystem rename is atomic on POSIX.
    if (std::rename(tmp.c_str(), path.c_str()) != 0) {
        std::remove(tmp.c_str());
        return false;
    }
    return true;
}

bool read(api::SchedulePayload& out, std::string& outEtag) {
    std::ifstream in(cachePath(), std::ios::binary);
    if (!in.is_open()) return false;

    std::ostringstream buffer;
    buffer << in.rdbuf();
    const std::string text = buffer.str();
    if (text.empty()) return false;

    // The cache stores the same version/type/daily/weekly shape as the API,
    // plus an "etag" field, so the API parser (which ignores unknown fields)
    // validates it directly.
    api::SchedulePayload parsed;
    if (!api::parseSchedulePayloadJson(text, parsed)) {
        return false;
    }

    radiantwave::json::JsonValue root;
    if (!radiantwave::json::parseDocument(text, root)) {
        return false;
    }
    outEtag = root.stringField("etag");
    out = std::move(parsed);
    return true;
}

bool clear() {
    return std::remove(cachePath().c_str()) == 0 || true;
}

} // namespace radiantwave::sync::schedule_cache