#include "gemini_app.h"

#include <Arduino.h>

#include <algorithm>

#include "gemini_url.h"
#include "text_wrap.h"
#include "ui/fonts.h"
#include "ui/theme.h"
#include "ui/widgets.h"

namespace roro {

using namespace gemini;

namespace {

constexpr int kUrlBar = 10;  // the small line with the URL at the top
constexpr int kMargin = 3;
constexpr const char* kStartUrl = GeminiService::kStartUrl;
constexpr size_t kMaxHistory = 20;  // Q77

// How each line type looks: its prefix, the indent of its wrapped rows, font and colour.
struct Style {
    const char* prefix;
    int indent;  // characters
    const lgfx::U8g2font* font;
    uint16_t color;
};

Style styleOf(LineType t) {
    switch (t) {
        case LineType::Heading1: return {"", 0, &fonts::bold, theme::kAccent};
        case LineType::Heading2: return {"", 0, &fonts::bold, theme::kText};
        case LineType::Heading3: return {"", 0, &fonts::bold, theme::kMuted};
        case LineType::ListItem: return {"\xC2\xB7 ", 2, &fonts::body, theme::kText};  // ·
        case LineType::Quote: return {"> ", 2, &fonts::body, theme::kMuted};
        case LineType::Link: return {"\xC2\xBB ", 2, &fonts::body, theme::kAccent};    // »
        case LineType::Preformatted: return {"", 0, &fonts::body, theme::kText};
        default: return {"", 0, &fonts::body, theme::kText};
    }
}

}  // namespace

void GeminiApp::onEnter() {
    if (page_.url.empty() && !loading_) navigate(kStartUrl, false);
    requestRedraw();
}

// The page's first heading, for a bookmark's label.
std::string GeminiApp::titleOf() const {
    for (size_t i = 0; i < page_.text.lineCount() && i < 40; i++)
        if (static_cast<LineType>(types_[i]) == LineType::Heading1) return lineAt(i).text;
    return "";
}

void GeminiApp::follow(const std::string& link) {
    std::string url = resolve(page_.base(), link);
    navigate(url, true, isSaved());  // inside a Saved Page, its saved links open offline (Q84)
}

void GeminiApp::showMessage(const std::string& url, const std::string& gemtext) {
    GeminiPage p;
    p.outcome = GeminiPage::Outcome::Ok;
    p.url = url;
    p.header.status = 20;
    p.text.append(gemtext.data(), gemtext.size());
    p.text.finish();
    show(std::move(p));
}

void GeminiApp::navigate(const std::string& target, bool remember, bool preferSaved) {
    bool local = target == kStartUrl || target.rfind("file://", 0) == 0;
    if (!isGemini(target) && !local) {
        status_ = "Not Gemini: " + target;
        statusMs_ = millis();
        requestRedraw();
        return;
    }
    if (!gemini_.fetch(target, preferSaved)) {
        status_ = "Busy: try again in a moment";
        statusMs_ = millis();
        return;
    }
    if (remember && !page_.url.empty()) {
        history_.push_back({page_.url, topRow_});
        if (history_.size() > kMaxHistory) history_.erase(history_.begin());
    }
    loading_ = true;
    loadingUrl_ = target;
    status_.clear();
    requestRedraw();
}

void GeminiApp::show(GeminiPage&& page) {
    page_ = std::move(page);
    windowLoading_ = false;
    analyse();
    topRow_ = hscroll_ = 0;
    selected_ = -1;
}

void GeminiApp::analyse() {
    types_.clear();
    links_.clear();
    // A window may start inside a preformatted block: the index says (bit 31).
    size_t entry = page_.windowStart / GeminiService::kIndexEvery;
    bool pre = page_.windowed && entry < page_.lineIndex.size() && (page_.lineIndex[entry] & 0x80000000u);
    for (size_t i = 0; i < page_.text.lineCount(); i++) {
        LineType t = parseGemLine(page_.text.line(i), pre).type;
        if (page_.header.mimeType() != "text/gemini") t = LineType::Preformatted;  // other text/*: as is
        types_.push_back(static_cast<uint8_t>(t));
        if (t == LineType::Link) links_.push_back(i);
    }
    layoutDirty_ = true;
    requestRedraw();
}

size_t GeminiApp::topLine() const {
    if (firstRow_.size() < 2) return page_.windowStart;
    size_t i = std::upper_bound(firstRow_.begin(), firstRow_.end() - 1, static_cast<uint32_t>(topRow_)) - firstRow_.begin();
    return page_.windowStart + (i > 0 ? i - 1 : 0);
}

void GeminiApp::requestWindow(size_t firstLine) {
    if (windowLoading_ || !gemini_.loadWindow(page_, firstLine)) return;
    windowLoading_ = true;
    keepLine_ = static_cast<long>(topLine());
    status_ = "Reading from the card...";
    statusMs_ = millis();
}

// A new window of the same page: same URL, history and position, other lines.
void GeminiApp::applyWindow(GeminiPage&& window) {
    windowLoading_ = false;
    status_.clear();
    page_.text = std::move(window.text);
    page_.windowStart = window.windowStart;
    page_.lineIndex = std::move(window.lineIndex);
    selected_ = -1;
    analyse();
}

void GeminiApp::update(uint32_t nowMs) {
    GeminiPage result;
    bool got = gemini_.takeResult(result);
    if (got && !result.windowOf.empty()) {
        windowLoading_ = false;
        if (result.windowOf == page_.backing) applyWindow(std::move(result));  // else: we've moved on
    } else if (got) {
        loading_ = false;
        std::string url = result.url;
        switch (result.outcome) {
            case GeminiPage::Outcome::CertificateChanged:
                pendingCert_ = std::move(result);
                certDialog_.reset(new DialogModel({"Cancel", "Trust it"}));
                break;
            case GeminiPage::Outcome::Failed:
                showMessage(url, "# Can't open this page\n" + result.error + "\n=> " + url + " Try again\n");
                break;
            case GeminiPage::Outcome::Ok:
                switch (result.header.category()) {
                    case Category::Success:
                        if (result.header.mimeType().rfind("text/", 0) == 0) show(std::move(result));
                        else {
                            std::string mime = result.header.mimeType();
                            showMessage(url, "# Not a text page\nThis is " + mime +
                                                 ", which the Cardputer can't show. s saves it to the card, in "
                                                 "/gemini/downloads.\n");
                            page_.header.meta = mime;  // so s knows to download it
                        }
                        break;
                    case Category::Input:
                        // Q72: ask, then request the same URL with the answer as its query.
                        inputOpen_ = true;
                        inputSensitive_ = result.header.sensitiveInput();
                        inputPrompt_ = result.header.meta;
                        inputUrl_ = url;
                        input_.setText("");
                        break;
                    default:
                        showMessage(url, "# " + std::to_string(result.header.status) + " " + result.header.meta +
                                             "\nThe server refused this page.\n=> " + url + " Try again\n");
                        break;
                }
                break;
        }
        requestRedraw();
    }
    // Signed: statusMs_ may be a few ms ahead of this pass's nowMs (set by a key handled after it).
    std::string message;
    if (gemini_.takeMessage(message)) {
        status_ = message;
        statusMs_ = millis();
        if (!reopen_.empty()) {  // a refreshed Saved Page: show the new copy
            navigate(reopen_, false);
            reopen_.clear();
        } else if (message == "Deleted") navigate(kStartUrl, false);
        requestRedraw();
    }
    if (!status_.empty() && static_cast<int32_t>(nowMs - statusMs_) > 4000) {
        status_.clear();
        requestRedraw();
    }
}

int GeminiApp::rowsOnScreen() const { return (theme::kContent.h - kUrlBar) / theme::kLineHeight; }

LineType typeOf(const std::vector<uint8_t>& types, size_t i) { return static_cast<LineType>(types[i]); }

GemLine GeminiApp::lineAt(size_t i) const {
    bool pre = typeOf(types_, i) == LineType::Preformatted;
    GemLine g = parseGemLine(page_.text.line(i), pre);
    if (typeOf(types_, i) == LineType::Preformatted) {
        g.type = LineType::Preformatted;
        g.text = page_.text.line(i);
    }
    return g;
}

// A line's rows, as drawn: prefix on the first, indent on the rest; preformatted lines don't wrap.
std::vector<std::string> GeminiApp::rowsOf(Canvas& c, size_t i) const {
    GemLine g = lineAt(i);
    if (g.type == LineType::PreToggle) return {};
    if (g.type == LineType::Preformatted) return {displayText(g.text)};
    Style st = styleOf(g.type);
    c.setFont(st.font);
    MeasureText measure = [&c](const std::string& s) { return static_cast<int>(c.textWidth(s.c_str())); };
    int width = theme::kWidth - 2 * kMargin;
    std::string indent(st.indent, ' ');
    std::vector<std::string> rows = wrapText(st.prefix + displayText(g.text), width, measure);
    if (rows.empty()) rows.push_back("");
    // Rows after the first: the exact rest of the text (wrapText keeps every space but the one it
    // breaks at), wrapped again, narrower, behind the indent.
    if (rows.size() > 1 && st.indent > 0) {
        std::string full = st.prefix + displayText(g.text);
        std::string rest = full.substr(rows[0].size());
        if (!rest.empty() && rest[0] == ' ') rest.erase(0, 1);
        std::vector<std::string> more = wrapText(rest, width - measure(indent), measure);
        rows.resize(1);
        for (auto& m : more) rows.push_back(indent + m);
    }
    return rows;
}

void GeminiApp::layout(Canvas& c) {
    firstRow_.assign(page_.text.lineCount() + 1, 0);
    uint32_t row = 0;
    for (size_t i = 0; i < page_.text.lineCount(); i++) {
        firstRow_[i] = row;
        row += rowsOf(c, i).size();
    }
    firstRow_.back() = row;
    layoutDirty_ = false;
}

void GeminiApp::scrollTo(int row) {
    int total = firstRow_.empty() ? 0 : static_cast<int>(firstRow_.back());
    // A windowed page: near either end of the window, read the next part from the card. The new
    // window starts a block before the line on top, so what's on screen stays.
    const size_t block = GeminiService::kIndexEvery;
    if (row + rowsOnScreen() > total - 2 && moreBelow()) {
        size_t line = topLine();
        requestWindow(line >= block ? line - line % block : 0);
    } else if (row < 0 && moreAbove()) {
        size_t line = topLine();
        size_t back = page_.text.lineCount() / 2;  // about half a window above
        requestWindow(line > back ? line - back : 0);
    }
    topRow_ = std::max(0, std::min(row, std::max(0, total - rowsOnScreen())));
    requestRedraw();
}

void GeminiApp::selectLink(int direction) {
    // A windowed page: past the window's last (or first) link, page on instead of wrapping.
    int last = static_cast<int>(links_.size()) - 1;
    if ((direction > 0 && moreBelow() && (links_.empty() || selected_ == last)) ||
        (direction < 0 && moreAbove() && (links_.empty() || selected_ == 0))) {
        selected_ = -1;
        scrollTo(topRow_ + direction * (rowsOnScreen() - 1));
        return;
    }
    if (links_.empty()) return;
    int count = static_cast<int>(links_.size());
    if (selected_ < 0) {
        // The first link on screen, or after it when going forward.
        selected_ = direction > 0 ? 0 : count - 1;
        for (int k = 0; k < count; k++)
            if (static_cast<int>(firstRow_[links_[k]]) >= topRow_) {
                selected_ = direction > 0 ? k : std::max(0, k - 1);
                break;
            }
    } else selected_ = (selected_ + direction + count) % count;
    int row = firstRow_[links_[selected_]];
    if (row < topRow_ || row >= topRow_ + rowsOnScreen()) scrollTo(row - 1);
    requestRedraw();
}

bool GeminiApp::onKey(const KeyEvent& e) {
    requestRedraw();
    if (certDialog_) {
        certDialog_->onKey(e);
        if (certDialog_->result() == DialogModel::kPending) return true;
        if (certDialog_->result() == 1) {
            gemini_.trust(pendingCert_.host, pendingCert_.port, pendingCert_.presented);
            navigate(pendingCert_.requested, false);
        }
        certDialog_.reset();
        return true;
    }
    if (deleteDialog_) {
        deleteDialog_->onKey(e);
        if (deleteDialog_->result() == DialogModel::kPending) return true;
        if (deleteDialog_->result() == 1) gemini_.deleteSaved(savedPathOf());
        deleteDialog_.reset();
        return true;
    }
    if (inputOpen_) {
        switch (e.key) {
            case Key::Char: input_.insert(e.ch); break;
            case Key::Delete: input_.backspace(); break;
            case Key::Left: input_.left(); break;
            case Key::Right: input_.right(); break;
            case Key::Back: inputOpen_ = false; break;
            case Key::Select:
                inputOpen_ = false;
                navigate(resolve(inputUrl_, "?" + encodeQuery(input_.text())));
                break;
            default: break;
        }
        return true;
    }
    if (addressOpen_) {
        switch (e.key) {
            case Key::Char: address_.insert(e.ch); break;
            case Key::Delete: address_.backspace(); break;
            case Key::Left: address_.left(); break;
            case Key::Right: address_.right(); break;
            case Key::Back: addressOpen_ = false; break;
            case Key::Select: {
                std::string url = address_.text();
                if (url.find("://") == std::string::npos) url = "gemini://" + url;
                addressOpen_ = false;
                navigate(url);
                break;
            }
            default: break;
        }
        return true;
    }
    switch (e.key) {
        case Key::Up: scrollTo(topRow_ - 1); return true;
        case Key::Down: scrollTo(topRow_ + 1); return true;
        case Key::Left: hscroll_ = std::max(0, hscroll_ - 8); return true;
        case Key::Right: hscroll_ += 8; return true;
        case Key::Tab: selectLink(e.shift ? -1 : 1); return true;
        case Key::Select:
            if (selected_ >= 0) follow(lineAt(links_[selected_]).url);
            return true;
        case Key::Back:
        case Key::Delete:
            if (loading_) {
                gemini_.cancel();
                return true;
            }
            if (history_.empty()) return e.key == Key::Delete;  // Back leaves the App
            {
                Visit v = history_.back();
                history_.pop_back();
                navigate(v.url, false);
                restoreRow_ = v.topRow;
            }
            return true;
        case Key::Char:
            switch (e.ch) {
                case ' ': scrollTo(topRow_ + rowsOnScreen() - 1); break;
                case 'g':
                    address_.setText(page_.url == kStartUrl || isSaved() ? "" : page_.url);
                    addressOpen_ = true;
                    break;
                case 'b':  // Q77
                    if (isGemini(page_.base())) gemini_.addBookmark(page_.base(), titleOf());
                    break;
                case 's':  // Q82, Q73
                    if (isSaved()) status_ = "Already saved; r refreshes it";
                    else if (!isGemini(page_.url)) status_ = "Only Gemini pages can be saved";
                    else if (page_.header.mimeType().rfind("text/", 0) == 0) gemini_.save(page_.url);
                    else gemini_.download(page_.url);
                    statusMs_ = millis();
                    break;
                case 'S': {  // Q83: this page and the gemtext it links to on the same capsule
                    Url here;
                    if (isSaved() || !parseUrl(page_.url, here)) break;
                    std::vector<std::string> links;
                    for (uint32_t i : links_) {
                        std::string target = resolve(page_.url, lineAt(i).url);
                        Url u;
                        if (isGemini(target) && parseUrl(target, u) && u.host == here.host && target != page_.url &&
                            std::find(links.begin(), links.end(), target) == links.end())
                            links.push_back(target);
                        if (static_cast<int>(links.size()) >= GeminiService::kMaxLinkedPages - 1) break;
                    }
                    gemini_.saveWithLinks(page_.url, links);
                    break;
                }
                case 'r':  // Q84: a fresh copy of a Saved Page
                    if (isSaved() && gemini_.refresh(savedPathOf())) reopen_ = page_.url;
                    break;
                case 'd':  // Q85
                    if (isSaved()) deleteDialog_.reset(new DialogModel({"Keep", "Delete"}));
                    break;
                default: break;
            }
            return true;
        default: return false;
    }
}

void GeminiApp::draw(Canvas& c) {
    const auto& area = theme::kContent;
    if (layoutDirty_) {
        layout(c);
        if (restoreRow_ >= 0 && !loading_) {
            scrollTo(restoreRow_);
            restoreRow_ = -1;
        }
        if (keepLine_ >= 0 && !windowLoading_) {  // a new window: back to the line that was on top
            long local = keepLine_ - static_cast<long>(page_.windowStart);
            if (local >= 0 && local < static_cast<long>(page_.text.lineCount())) topRow_ = firstRow_[local];
            keepLine_ = -1;
        }
    }

    // The URL bar: what's shown, or what's loading, or a passing message.
    c.setFont(&fonts::small);
    c.setTextDatum(top_left);
    std::string bar = loading_ ? "Loading " + loadingUrl_
                      : !status_.empty() ? status_
                      : isSaved() ? "saved " + page_.savedOn + ": " + page_.savedFrom
                                  : page_.url;
    c.setTextColor(loading_ || !status_.empty() ? theme::kWarning : theme::kMuted);
    c.drawString(displayText(bar).substr(0, 47).c_str(), kMargin, area.y + 1);

    int rows = rowsOnScreen(), y0 = area.y + kUrlBar;
    // The first source line on screen: the last whose first row is at or above topRow_.
    size_t i = std::upper_bound(firstRow_.begin(), firstRow_.end() - 1, static_cast<uint32_t>(topRow_)) -
               firstRow_.begin();
    i = i > 0 ? i - 1 : 0;
    int row = topRow_;
    while (i < page_.text.lineCount() && row < topRow_ + rows) {
        int skip = row - static_cast<int>(firstRow_[i]);
        int lineRows = static_cast<int>(firstRow_[i + 1] - firstRow_[i]);
        if (lineRows > 0) {
            drawLine(c, i, skip, y0 + (row - topRow_) * theme::kLineHeight, topRow_ + rows - row);
            row += lineRows - skip;
        }
        i++;
    }
    if (page_.truncated && row < topRow_ + rows) {
        c.setFont(&fonts::small);
        c.setTextColor(theme::kWarning);
        c.drawString(("Cut short: " + page_.truncatedWhy).substr(0, 47).c_str(), kMargin,
                     y0 + (row - topRow_) * theme::kLineHeight + 2);
    }
    // Scroll position, on the right edge: over the whole page, also when only a window is in memory.
    int total = static_cast<int>(firstRow_.back());
    int h = area.h - kUrlBar;
    if (page_.windowed && page_.totalLines > 0) {
        int barH = std::max(6, static_cast<int>(h * page_.text.lineCount() / page_.totalLines / 3));
        int y = static_cast<int>((h - barH) * topLine() / std::max<size_t>(1, page_.totalLines - 1));
        c.fillRect(area.w - 2, y0 + y, 2, barH, theme::kMuted);
    } else if (total > rows) {
        int barH = std::max(6, h * rows / total);
        c.fillRect(area.w - 2, y0 + (h - barH) * topRow_ / std::max(1, total - rows), 2, barH, theme::kMuted);
    }

    if (addressOpen_) {
        theme::Rect box{2, area.y + area.h / 2 - 12, area.w - 4, theme::kLineHeight + 4};
        c.fillRect(box.x - 2, box.y - 12, box.w + 4, box.h + 14, theme::kBackground);
        c.setFont(&fonts::small);
        c.setTextColor(theme::kMuted);
        c.drawString("Go to (Enter, or ` to cancel)", box.x, box.y - 10);
        widgets::lineEditor(c, address_, box);
    }
    if (inputOpen_) {
        theme::Rect box{2, area.y + area.h / 2 - 4, area.w - 4, theme::kLineHeight + 4};
        c.fillRect(0, box.y - 26, area.w, box.h + 28, theme::kBackground);
        c.setFont(&fonts::body);
        c.setTextColor(theme::kText);
        c.drawString(displayText(inputPrompt_).substr(0, 39).c_str(), box.x, box.y - 22);
        c.setFont(&fonts::small);
        c.setTextColor(theme::kMuted);
        c.drawString(inputSensitive_ ? "(hidden) Enter sends, ` cancels" : "Enter sends, ` cancels", box.x, box.y - 9);
        if (inputSensitive_) {
            LineEditor masked(1024);
            masked.setText(std::string(input_.text().size(), '*'));
            widgets::lineEditor(c, masked, box);
        } else widgets::lineEditor(c, input_, box);
    }
    if (deleteDialog_) widgets::dialog(c, "Delete this Saved Page?", page_.savedFrom, *deleteDialog_);
    if (certDialog_)
        widgets::dialog(c, "Certificate changed",
                        pendingCert_.host + " now shows a different certificate. Was " + pendingCert_.pinned.substr(0, 16) +
                            "..., now " + pendingCert_.presented.substr(0, 16) + "...",
                        *certDialog_);
}

void GeminiApp::drawLine(Canvas& c, size_t i, int firstRow, int y, int rowsLeft) {
    GemLine g = lineAt(i);
    Style st = styleOf(g.type);
    bool isSelected = selected_ >= 0 && links_[selected_] == i;
    std::vector<std::string> rows = rowsOf(c, i);
    c.setFont(st.font);
    c.setTextDatum(top_left);
    for (int r = firstRow; r < static_cast<int>(rows.size()) && r - firstRow < rowsLeft; r++) {
        int ry = y + (r - firstRow) * theme::kLineHeight;
        if (isSelected) c.fillRect(0, ry, theme::kWidth - 3, theme::kLineHeight, theme::kSelection);
        c.setTextColor(isSelected ? theme::kText : st.color);
        std::string text = rows[r];
        if (g.type == LineType::Preformatted) text = hscroll_ < static_cast<int>(text.size()) ? text.substr(hscroll_) : "";
        c.drawString(text.c_str(), kMargin, ry + 1);
    }
}

}  // namespace roro