#include <regex>

#include "routes.h"
#include "../blankie/murl.h"
#include "../blankie/escape.h"
#include "../blankie/unescape.h"
#include "../servehelper.h"
#include "../numberhelper.h"
#include "../pixivclient.h"

static inline Element generate_user_link(const httplib::Request& req, const Config& config, const Illust& illust);
static inline Element generate_images(const httplib::Request& req, const Config& config, const Illust& illust);
static inline Element generate_preview_images(const httplib::Request& req, const Config& config, const Illust& illust);
static inline Element generate_illust_tags(const httplib::Request& req, const Config& config, const Illust& illust);
static inline blankie::html::HTMLString fix_description_links(const httplib::Request& req, const Config& config, blankie::html::HTMLString str);
static inline std::string generate_description_text(const httplib::Request& req, const Config& config, blankie::html::HTMLString description);
static inline Nodes generate_ogp_nodes(const httplib::Request& req, const Config& config, const Illust& illust, bool preview);

static inline bool is_true(const std::string& str);
static inline std::string time_to_string(time_t time);
static inline std::string proxy_pixiv_url(const httplib::Request& req, const Config& config, blankie::murl::Url url);

void artworks_route(const httplib::Request& req, httplib::Response& res, const Config& config, PixivClient& pixiv_client) {
    uint64_t illust_id = to_ull(req.matches.str(1));
    bool preview = is_true(req.get_param_value("preview"));
    Illust illust;

    try {
        illust = pixiv_client.get_illust(illust_id);
    } catch (const PixivException& e) {
        if (e.status == 404) {
            res.status = 404;
            serve_error(req, res, config, "404: Illust not found", e.what());
        } else {
            res.status = 500;
            serve_error(req, res, config, "500: Internal server error", "Failed to fetch illust information", e.what());
        }
        return;
    } catch (const std::exception& e) {
        res.status = 500;
        serve_error(req, res, config, "500: Internal server error", "Failed to fetch illust information", e.what());
        return;
    }

    Element body("body", {
        Element("h2", {illust.title}),
        generate_user_link(req, config, illust),
        Element("br"),
        !preview ? generate_images(req, config, illust) : generate_preview_images(req, config, illust),
        Element("br")
    });
    if (illust.comment_html) {
        body.nodes.push_back(Element("p", {fix_description_links(req, config, blankie::html::HTMLString(*illust.comment_html))}));
    }
    body.nodes.push_back(generate_illust_tags(req, config, illust));
    body.nodes.push_back(Element("p", {time_to_string(illust.upload_time)}));
    serve(req, res, config, illust.title, std::move(body), generate_ogp_nodes(req, config, illust, preview));
}

static inline Element generate_user_link(const httplib::Request& req, const Config& config, const Illust& illust) {
    std::string profile_picture = proxy_image_url(req, config, illust.user_profile_pictures.thumbnail_or_original().url);
    std::string user_link = get_origin(req, config) + "/users/" + std::to_string(illust.user_id);

    return Element("a", {{"class", "user_metadata"}, {"href", std::move(user_link)}}, {
        Element("img", {{"class", "user_profile_picture small"}, {"loading", "lazy"}, {"src", std::move(profile_picture)}}, {}),
        Element("b", {illust.user_display_name})
    });
}

static inline Element generate_images(const httplib::Request& req, const Config& config, const Illust& illust) {
    using namespace std::string_literals;

    Element div("div", {{"class", "illust-images"}}, {});
    bool show_pages = illust.images.size() > 1;

    if (show_pages) {
        div.nodes.push_back(Element("a", {{"href", "?preview=1"}}, {"Preview Images"}));
    }
    div.nodes.reserve(div.nodes.size() + (show_pages ? illust.images.size() * 2 : illust.images.size()));
    for (size_t i = 0; i < illust.images.size(); i++) {
        const Images& images = illust.images[i];
        const Image& thumbnail = images.thumbnail_or_original();
        const Image& original = images.original_or_thumbnail();
        std::string id = std::to_string(i + 1);

        if (show_pages) {
            div.nodes.push_back(Element("a", {{"class", "landmark"}, {"href", "#"s + id}}, {id, "/", std::to_string(illust.images.size())}));
        }

        Element img("img", {{"loading", "lazy"}, {"id", std::move(id)}, {"src", proxy_image_url(req, config, thumbnail.url)}}, {});
        if (thumbnail.size) {
            img.attributes.push_back({"width", std::to_string(thumbnail.size->first)});
            img.attributes.push_back({"height", std::to_string(thumbnail.size->second)});
        }
        div.nodes.push_back(Element("a", {{"href", proxy_image_url(req, config, original.url)}}, {
            std::move(img)
        }));
    }

    return div;
}

static inline Element generate_preview_images(const httplib::Request& req, const Config& config, const Illust& illust) {
    std::string no_preview_link = get_origin(req, config) + "/artworks/" + std::to_string(illust.illust_id);
    Element div("div", {
        Element("a", {{"class", "center"}, {"href", no_preview_link}}, {"Go back"}),
        Element("br")
    });
    Element grid("div", {{"class", "grid"}}, {});

    grid.nodes.reserve(illust.images.size());
    for (size_t i = 0; i < illust.images.size(); i++) {
        const Images& images = illust.images[i];
        std::string thumbnail = proxy_image_url(req, config, images.thumbnail_or_original(1).url);
        std::string link = no_preview_link + '#' + std::to_string(i + 1);

        grid.nodes.push_back(Element("a", {{"href", std::move(link)}}, {
            Element("img", {{"loading", "lazy"}, {"src", std::move(thumbnail)}}, {})
        }));
    }

    div.nodes.push_back(std::move(grid));
    return div;
}

static inline Element generate_illust_tags(const httplib::Request& req, const Config& config, const Illust& illust) {
    Element div("div", {{"class", "illust-tags"}}, {});

    if (illust.ai_generated) {
        div.nodes.push_back(Element("b", {"AI-Generated "}));
    }
    div.nodes.reserve(div.nodes.size() + illust.tags.size());
    for (const Tag& i : illust.tags) {
        std::string tag = [&]() {
            if (i.english) return *i.english;
            return i.japanese;
        }();

        div.nodes.push_back(Element("a", {{"href", get_origin(req, config) + "/tags/" + blankie::murl::escape(i.japanese)}}, {
            "#", std::move(tag)
        }));
    }

    return div;
}

const std::regex start_link_regex("<a href=\"([^\"]+?)\"(?: target=\"_blank\")?>");
static inline blankie::html::HTMLString fix_description_links(const httplib::Request& req, const Config& config, blankie::html::HTMLString str) {
    using namespace std::string_literals;

    blankie::html::HTMLString out;
    std::smatch sm;

    out.str.reserve(str.str.size());
    while (std::regex_search(str.str, sm, start_link_regex)) {
        out.str += sm.prefix();

        std::string url_str;
        blankie::murl::Url url(sm.str(1));
        if (url.is_host_equal("pixiv.net") || url.is_host_equal("www.pixiv.net")) {
            url_str = proxy_pixiv_url(req, config, std::move(url));
        } else if (url.path == "/jump.php") {
            url_str = blankie::murl::unescape(std::move(url.query));
        } else {
            url_str = url.to_string();
        }
        out.str += "<a href=\""s + blankie::html::escape(std::move(url_str)) + "\">";

        str.str = sm.suffix();
    }
    out.str += std::move(str.str);

    return out;
}

const std::regex link_regex("<a href=\"([^\"]+?)\">.+?</a>");
const std::regex tag_regex("<(.+?)>");
static inline std::string generate_description_text(const httplib::Request& req, const Config& config, blankie::html::HTMLString description) {
    description = fix_description_links(req, config, std::move(description));

    std::string new_description;
    std::smatch sm;

    new_description.reserve(description.str.size());
    while (std::regex_search(description.str, sm, link_regex)) {
        new_description += sm.prefix();
        new_description += sm.str(1);
        description.str = sm.suffix();
    }
    new_description += std::move(description.str);

    description.str = std::move(new_description);
    new_description.reserve(description.str.size());
    while (std::regex_search(description.str, sm, tag_regex)) {
        new_description += sm.prefix();
        if (sm.str(1) == "br /") {
            new_description += '\n';
        }
        description.str = sm.suffix();
    }
    new_description += std::move(description.str);

    return blankie::html::unescape(std::move(new_description));
}

static inline Nodes generate_ogp_nodes(const httplib::Request& req, const Config& config, const Illust& illust, bool preview) {
    std::string url = get_origin(req, config) + "/artworks/" + std::to_string(illust.illust_id);
    if (preview) {
        url += "?preview=1";
    }
    Nodes nodes({
        Element("meta", {{"property", "og:title"}, {"content", illust.title}}, {}),
        Element("meta", {{"property", "og:type"}, {"content", "photo"}}, {}),
        Element("meta", {{"property", "og:site_name"}, {"content", "Pixwhile"}}, {}),
        Element("meta", {{"property", "og:url"}, {"content", std::move(url)}}, {})
    });
    if (illust.comment_html) {
        nodes.push_back(Element("meta", {{"property", "og:description"}, {"content", generate_description_text(req, config, blankie::html::HTMLString(*illust.comment_html))}}, {}));
    }

    // i don't even know what multiple og:images do anymore
    // https://stackoverflow.com/questions/13424780/facebook-multiple-ogimage-tags-which-is-default
    nodes.reserve(nodes.size() + illust.images.size() * 3);
    for (const Images& images : illust.images) {
        const Image& image = images.thumbnail_or_original();
        nodes.push_back(Element("meta", {{"property", "og:image"}, {"content", proxy_image_url(req, config, image.url)}}, {}));
        if (image.size) {
            nodes.push_back(Element("meta", {{"property", "og:image:width"}, {"content", std::to_string(image.size->first)}}, {}));
            nodes.push_back(Element("meta", {{"property", "og:image:height"}, {"content", std::to_string(image.size->second)}}, {}));
        }
    }

    return nodes;
}

static inline bool is_true(const std::string& str) {
    return !str.empty() && str != "0" && str != "false" && str != "no";
}

static inline std::string time_to_string(time_t time) {
    struct tm tm;
    char str[1024] = {0};

    if (!gmtime_r(&time, &tm)) {
        return std::to_string(time);
    }
    size_t len = strftime(str, 1024, "%F %H:%M:%S %z", &tm);
    if (len == 0) {
        return std::to_string(time);
    }

    return std::string(str, len);
}

static inline std::string proxy_pixiv_url(const httplib::Request& req, const Config& config, blankie::murl::Url url) {
    if (url.path.size() >= 4 && url.path.starts_with("/en/")) {
        url.path.erase(0, 3);
    } else if (url.path.size() == 3 && url.path == "/en") {
        url.path = '/';
    }

    // TODO strip the lang query parameter
    return proxy_url(get_origin(req, config), std::move(url));
}