#include "xml.hpp"

#include <charconv>
#include <sstream>
#include <stdexcept>
#include <utility>

#include "util/stringutil.hpp"
#include "coders/BasicParser.hpp"

using namespace xml;

Attribute::Attribute(std::string name, std::string text)
    : name(std::move(name)), text(std::move(text)) {
}

const std::string& Attribute::getName() const {
    return name;
}

const std::string& Attribute::getText() const {
    return text;
}

int64_t Attribute::asInt() const {
    return std::stoll(text);
}

double Attribute::asFloat() const {
    return util::parse_double(text);
}

bool Attribute::asBool() const {
    return text == "true" || text == "1";
}

/* Read 2d vector formatted `x,y`*/
glm::vec2 Attribute::asVec2() const {
    size_t pos = text.find(',');
    if (pos == std::string::npos) {
        return glm::vec2(util::parse_double(text, 0, text.length()));
    }
    return glm::vec2(
        util::parse_double(text, 0, pos),
        util::parse_double(text, pos + 1, text.length() - pos - 1)
    );
}

/* Read 3d vector formatted `x,y,z`*/
glm::vec3 Attribute::asVec3() const {
    size_t pos1 = text.find(',');
    if (pos1 == std::string::npos) {
        return glm::vec3(util::parse_double(text, 0, text.length()));
    }
    size_t pos2 = text.find(',', pos1 + 1);
    if (pos2 == std::string::npos) {
        throw std::runtime_error("invalid vec3 value " + util::quote(text));
    }
    return glm::vec3(
        util::parse_double(text, 0, pos1),
        util::parse_double(text, pos1 + 1, pos2),
        util::parse_double(text, pos2 + 1, text.length() - pos2 - 1)
    );
}

/* Read 4d vector formatted `x,y,z,w`*/
glm::vec4 Attribute::asVec4() const {
    size_t pos1 = text.find(',');
    if (pos1 == std::string::npos) {
        return glm::vec4(util::parse_double(text, 0, text.length()));
    }
    size_t pos2 = text.find(',', pos1 + 1);
    if (pos2 == std::string::npos) {
        throw std::runtime_error("invalid vec4 value " + util::quote(text));
    }
    size_t pos3 = text.find(',', pos2 + 1);
    if (pos3 == std::string::npos) {
        throw std::runtime_error("invalid vec4 value " + util::quote(text));
    }
    return glm::vec4(
        util::parse_double(text, 0, pos1),
        util::parse_double(text, pos1 + 1, pos2 - pos1 - 1),
        util::parse_double(text, pos2 + 1, pos3 - pos2 - 1),
        util::parse_double(text, pos3 + 1, text.length() - pos3 - 1)
    );
}

/* Read RGBA color. Supported formats:
   - "#RRGGBB" or "#RRGGBBAA" hex color */
glm::vec4 Attribute::asColor() const {
    if (text[0] == '#') {
        if (text.length() != 7 && text.length() != 9) {
            throw std::runtime_error("#RRGGBB or #RRGGBBAA required");
        }
        int a = 255;
        int r = (std::max(0, hexchar2int(text[1])) << 4) | hexchar2int(text[2]);
        int g = (std::max(0, hexchar2int(text[3])) << 4) | hexchar2int(text[4]);
        int b = (std::max(0, hexchar2int(text[5])) << 4) | hexchar2int(text[6]);
        if (text.length() == 9) {
            a = (std::max(0, hexchar2int(text[7])) << 4) | hexchar2int(text[8]);
        }
        return glm::vec4(r / 255.f, g / 255.f, b / 255.f, a / 255.f);
    } else {
        return asVec4() / 255.f;
    }
}

Node::Node(std::string tag) : tag(std::move(tag)) {
}

void Node::add(std::unique_ptr<Node> element) {
    elements.push_back(std::move(element));
}

void Node::set(const std::string& name, const std::string& text) {
    attrs[name] = Attribute(name, text);
}

const std::string& Node::getTag() const {
    return tag;
}

const Attribute& Node::attr(const std::string& name) const {
    auto found = attrs.find(name);
    if (found == attrs.end()) {
        throw std::runtime_error(
            "element <" + tag + " ...> missing attribute " + name
        );
    }
    return found->second;
}

Attribute Node::attr(const std::string& name, const std::string& def) const {
    auto found = attrs.find(name);
    if (found == attrs.end()) {
        return Attribute(name, def);
    }
    return found->second;
}

bool Node::has(const std::string& name) const {
    auto found = attrs.find(name);
    return found != attrs.end();
}

Node& Node::sub(size_t index) {
    return *elements.at(index);
}

const Node& Node::sub(size_t index) const {
    return *elements.at(index);
}

size_t Node::size() const {
    return elements.size();
}

const std::vector<std::unique_ptr<Node>>& Node::getElements() const {
    return elements;
}

const std::unordered_map<std::string, Attribute>& Node::getAttributes() const {
    return attrs;
}

Document::Document(std::string version, std::string encoding)
    : version(std::move(version)), encoding(std::move(encoding)) {
}

void Document::setRoot(std::unique_ptr<Node> element) {
    root = std::move(element);
}

const Node* Document::getRoot() const {
    return root.get();
}

const std::string& Document::getVersion() const {
    return version;
}

const std::string& Document::getEncoding() const {
    return encoding;
}

inline bool is_xml_identifier_start(char c) {
    return is_identifier_start(c) || c == ':';
}

inline bool is_xml_identifier_part(char c) {
    return is_identifier_part(c) || c == '-' || c == '.' || c == ':';
}

namespace {
class Parser : BasicParser<char> {
    std::unique_ptr<Document> document;

    std::unique_ptr<Node> parseOpenTag() {
        std::string tag = parseXMLName();
        auto node = std::make_unique<Node>(tag);

        char c;
        while (true) {
            skipWhitespace();
            c = peek();
            if (c == '/' || c == '>' || c == '?') break;
            std::string attrname = parseXMLName();
            std::string attrtext = "";
            skipWhitespace();
            if (peek() == '=') {
                nextChar();
                skipWhitespace();

                char quote = peek();
                if (quote != '\'' && quote != '"') {
                    throw error("string literal expected");
                }
                skip(1);
                attrtext = parseString(quote);
            }
            node->set(attrname, attrtext);
        }
        return node;
    }

    std::unique_ptr<Node> parseElement() {
        // text element
        if (peek() != '<') {
            auto element = std::make_unique<Node>("#");
            auto text = parseText();
            util::replaceAll(text, "&quot;", "\"");
            util::replaceAll(text, "&apos;", "'");
            util::replaceAll(text, "&lt;", "<");
            util::replaceAll(text, "&gt;", ">");
            util::replaceAll(text, "&amp;", "&");
            element->set("#", text);
            return element;
        }
        nextChar();

        // <!--element-->
        if (peek() == '!') {
            if (isNext("!DOCTYPE ")) {
                throw error("XML DTD is not supported yet");
            }
            parseComment();
            return nullptr;
        }

        auto element = parseOpenTag();
        char c = nextChar();

        // <element/>
        if (c == '/') {
            expect('>');
        }
        // <element>...</element>
        else if (c == '>') {
            skipWhitespace();
            while (!isNext("</")) {
                auto sub = parseElement();
                if (sub) {
                    element->add(std::move(sub));
                }
                skipWhitespace();
            }
            skip(2);
            expect(element->getTag());
            expect('>');
        }
        // <element?>
        else {
            throw error("invalid syntax");
        }
        return element;
    }

    void parseDeclaration() {
        std::string version = "1.0";
        std::string encoding = "UTF-8";
        expect('<');
        if (peek() == '?') {
            nextChar();
            auto node = parseOpenTag();
            expect("?>");
            if (node->getTag() != "xml") {
                throw error("invalid declaration");
            }
            version = node->attr("version", version).getText();
            encoding = node->attr("encoding", encoding).getText();
            if (encoding != "utf-8" && encoding != "UTF-8") {
                throw error("UTF-8 encoding is only supported");
            }
        } else {
            goBack();
        }
        document = std::make_unique<Document>(version, encoding);
    }

    void parseComment() {
        expect("!--");
        if (skipTo("-->")) {
            skip(3);
        } else {
            throw error("comment close missing");
        }
    }

    std::string parseText() {
        size_t start = pos;
        while (hasNext()) {
            char c = peek();
            if (c == '<') {
                break;
            }
            nextChar();
        }
        return Parser("[string]", std::string(source.substr(start, pos - start)))
            .parseString('\0', false);
    }

    std::string parseXMLName() {
        char c = peek();
        if (!is_xml_identifier_start(c)) {
            throw error("identifier expected");
        }
        int start = pos;
        while (hasNext() && is_xml_identifier_part(source[pos])) {
            pos++;
        }
        return std::string(source.substr(start, pos - start));
    }
public:
    Parser(std::string_view filename, std::string_view source)
        : BasicParser(filename, source) {
    }

    std::unique_ptr<Document> parse() {
        parseDeclaration();

        std::unique_ptr<Node> root;
        while (root == nullptr) {
            root = parseElement();
        }
        document->setRoot(std::move(root));
        return std::move(document);
    }
};
}

std::unique_ptr<Document> xml::parse(
    std::string_view filename, std::string_view source
) {
    Parser parser(filename, source);
    return parser.parse();
}

namespace {
class VcmParser : public BasicParser<char> {
public:
    VcmParser(std::string_view filename, std::string_view source)
        : BasicParser(filename, source) {
        document = std::make_unique<Document>("1.0", "UTF-8");
        hashComment = true;
    }

    std::string parseValue() {
        char c = peek();
        if (c == '"' || c == '\'') {
            nextChar();
            return parseString(c);
        }
        if (c == '(') {
            nextChar();
            // TODO: replace with array parsing after moving to dv::value's
            std::string value = std::string(readUntil(')'));
            expect(')');
            return value;
        }
        return std::string(readUntilWhitespace());
    }

    void parseSubElements(Node& node) {
        skipWhitespace();
        while (hasNext()) {
            if (peek() != '@') {
                throw error("unexpected character in element");
            }
            nextChar();
            auto subnodePtr = std::make_unique<Node>(parseName());
            auto subnode = subnodePtr.get();
            node.add(std::move(subnodePtr));

            skipWhitespace();
            while (hasNext() && peek() != '@' && peek() != '{' && peek() != '}') {
                std::string attrname = parseName();
                skipWhitespace();
                std::string value = parseValue();
                subnode->set(attrname, value);
                skipWhitespace();
            }
            if (!hasNext()) {
                break;
            }
            char c = peek();
            if (c == '{') {
                nextChar();
                parseSubElements(*subnode);
                expect('}');
                skipWhitespace();
            } else if (c == '}') {
                break;
            }
        }
    }

    std::unique_ptr<Document> parse(const std::string& rootTag) {
        auto root = std::make_unique<Node>(rootTag);
        parseSubElements(*root);
        document->setRoot(std::move(root));
        return std::move(document);
    }
private:
    std::unique_ptr<Document> document;
};
}

std::unique_ptr<Document> xml::parse_vcm(
    std::string_view filename, std::string_view source, std::string_view tag
) {
    VcmParser parser(filename, source);
    return parser.parse(std::string(tag));
}

inline void newline(
    std::stringstream& ss, bool nice, const std::string& indentStr, int indent
) {
    if (!nice) return;
    ss << '\n';
    for (int i = 0; i < indent; i++) {
        ss << indentStr;
    }
}

static void stringifyElement(
    std::stringstream& ss,
    const Node& element,
    bool nice,
    const std::string& indentStr,
    int indent
) {
    if (element.isText()) {
        std::string text = element.attr("#").getText();
        util::replaceAll(text, "&", "&amp;");
        util::replaceAll(text, "\"", "&quot;");
        util::replaceAll(text, "'", "&apos;");
        util::replaceAll(text, "<", "&lt;");
        util::replaceAll(text, ">", "&gt;");
        ss << text;
        return;
    }
    const std::string& tag = element.getTag();

    ss << '<' << tag;
    auto& attrs = element.getAttributes();
    if (!attrs.empty()) {
        ss << ' ';
        int count = 0;
        for (auto& entry : attrs) {
            auto attr = entry.second;
            ss << attr.getName();
            if (!attr.getText().empty()) {
                ss << "=" << util::escape(attr.getText());
            }
            if (count + 1 < int(attrs.size())) {
                ss << " ";
            }
            count++;
        }
    }
    auto& elements = element.getElements();
    if (elements.size() == 1 && elements[0]->isText()) {
        ss << ">";
        stringifyElement(ss, *elements[0], nice, indentStr, indent + 1);
        ss << "</" << tag << ">";
        return;
    }
    if (!elements.empty()) {
        ss << '>';
        for (auto& sub : elements) {
            newline(ss, nice, indentStr, indent + 1);
            stringifyElement(ss, *sub, nice, indentStr, indent + 1);
        }
        newline(ss, nice, indentStr, indent);
        ss << "</" << tag << ">";

    } else {
        ss << "/>";
    }
}

std::string xml::stringify(
    const Document& document, bool nice, const std::string& indentStr
) {
    std::stringstream ss;

    // XML declaration
    ss << "<?xml version=\"" << document.getVersion();
    ss << "\" encoding=\"UTF-8\" ?>";
    newline(ss, nice, indentStr, 0);

    stringifyElement(ss, *document.getRoot(), nice, indentStr, 0);

    return ss.str();
}