#include "file_list.h"

#include <algorithm>
#include <cctype>
#include <cstdio>
#include <cstring>
#include <ctime>

namespace roro::files {

namespace {

// Names compare letters only, whatever the case; ties by the bytes, so the order is total.
int compareNames(const char* a, const char* b) {
    for (const char *x = a, *y = b;; ++x, ++y) {
        int cx = std::tolower(static_cast<unsigned char>(*x)), cy = std::tolower(static_cast<unsigned char>(*y));
        if (cx != cy) return cx < cy ? -1 : 1;
        if (!cx) break;
    }
    return std::strcmp(a, b);
}

constexpr uint32_t kYear2020 = 1577836800;

std::string sizeText(uint32_t bytes) {
    char s[16];
    if (bytes < 1024) std::snprintf(s, sizeof s, "%u B", static_cast<unsigned>(bytes));
    else if (bytes < 10 * 1024) std::snprintf(s, sizeof s, "%.1f KB", bytes / 1024.0);
    else if (bytes < 1024 * 1024) std::snprintf(s, sizeof s, "%u KB", static_cast<unsigned>(bytes / 1024));
    else if (bytes < 10u * 1024 * 1024) std::snprintf(s, sizeof s, "%.1f MB", bytes / 1048576.0);
    else if (bytes < 1024u * 1024 * 1024) std::snprintf(s, sizeof s, "%u MB", static_cast<unsigned>(bytes / 1048576));
    else std::snprintf(s, sizeof s, "%.1f GB", bytes / 1073741824.0);
    return s;
}

}  // namespace

void FileList::clear() {
    std::vector<Entry>().swap(entries_);
    std::vector<uint16_t>().swap(order_);
    std::vector<char>().swap(names_);
    more_ = wasted_ = 0;
}

bool FileList::before(const Entry& a, const Entry& b, FileSort by) const {
    if (a.folder != b.folder) return a.folder;
    if (!a.folder) {
        if (by == FileSort::Date && a.modified != b.modified) return a.modified > b.modified;
        if (by == FileSort::Size && a.size != b.size) return a.size > b.size;
    }
    return compareNames(names_.data() + a.name, names_.data() + b.name) < 0;
}

void FileList::add(const char* name, uint32_t size, uint32_t modified, bool folder) {
    size_t len = std::strlen(name) + 1;
    if (entries_.size() >= kMax) {
        // Full: the new entry takes the place of the one that sorts last by name, if it sorts
        // before it. The old name's bytes stay in the buffer until there's enough waste to pack.
        more_++;
        size_t last = 0;
        for (size_t i = 1; i < entries_.size(); i++)
            if (before(entries_[last], entries_[i], FileSort::Name)) last = i;
        Entry candidate{static_cast<uint32_t>(names_.size()), size, modified, folder};
        names_.insert(names_.end(), name, name + len);
        if (!before(candidate, entries_[last], FileSort::Name)) {
            names_.resize(names_.size() - len);
            return;
        }
        wasted_ += std::strlen(names_.data() + entries_[last].name) + 1;
        entries_[last] = candidate;
        if (wasted_ > 2048) compact();
        return;
    }
    if (entries_.empty()) {
        entries_.reserve(32);
        names_.reserve(512);
    }
    entries_.push_back({static_cast<uint32_t>(names_.size()), size, modified, folder});
    names_.insert(names_.end(), name, name + len);
    order_.push_back(static_cast<uint16_t>(order_.size()));
}

void FileList::compact() {
    std::vector<char> packed;
    packed.reserve(names_.size() - wasted_);
    for (Entry& e : entries_) {
        const char* n = names_.data() + e.name;
        e.name = static_cast<uint32_t>(packed.size());
        packed.insert(packed.end(), n, n + std::strlen(n) + 1);
    }
    names_.swap(packed);
    wasted_ = 0;
}

void FileList::sort(FileSort by) {
    if (wasted_) compact();
    names_.shrink_to_fit();
    entries_.shrink_to_fit();
    order_.resize(entries_.size());
    for (size_t i = 0; i < order_.size(); i++) order_[i] = static_cast<uint16_t>(i);
    std::sort(order_.begin(), order_.end(), [&](uint16_t a, uint16_t b) { return before(entries_[a], entries_[b], by); });
}

int FileList::find(const std::string& name) const {
    for (size_t i = 0; i < order_.size(); i++)
        if (name == this->name(i)) return static_cast<int>(i);
    return -1;
}

size_t FileList::bytes() const {
    return entries_.capacity() * sizeof(Entry) + order_.capacity() * sizeof(uint16_t) + names_.capacity();
}

std::string formatStamp(uint32_t modified) {
    if (modified < kYear2020) return "-";
    time_t t = static_cast<time_t>(modified);
    struct tm local;
    localtime_r(&t, &local);
    char s[20];
    std::snprintf(s, sizeof s, "%04d-%02d-%02d %02d:%02d", local.tm_year + 1900, local.tm_mon + 1, local.tm_mday, local.tm_hour,
                  local.tm_min);
    return s;
}

std::string rowDetail(bool folder, uint32_t size, uint32_t modified) {
    if (folder) return "folder";
    std::string stamp = formatStamp(modified);
    return sizeText(size) + "  " + (stamp == "-" ? stamp : stamp.substr(0, 10));
}

std::string fitName(const std::string& name, size_t maxChars) {
    if (name.size() <= maxChars || maxChars < 8) return name.substr(0, maxChars);
    size_t tail = std::min<size_t>(6, maxChars / 3), head = maxChars - tail - 2;
    return name.substr(0, head) + ".." + name.substr(name.size() - tail);
}

}  // namespace roro::files