#include <XEP393.h>

#include <StringSplit.h>

#include <Cytoplasm/Memory.h>
#include <Cytoplasm/Array.h>
#include <Cytoplasm/Str.h>
#include <Cytoplasm/Log.h>

#include <string.h>
#include <ctype.h>

static XEP393Element *
CreateElementVessel(XEP393Element *parent, XEP393Type type)
{
    XEP393Element *ret = Malloc(sizeof(*ret));
    ret->parent = parent;
    ret->type = type;
    ret->children = ArrayCreate();
    ret->text_data = NULL;

    if (parent)
    {
        ArrayAdd(parent->children, ret);
    }
    return ret;
}
static void
XEP393FreeElementBase(XEP393Element *element, bool unlink)
{
    size_t i, len;
    if (!element)
    {
        return;
    }

    len = ArraySize(element->children);
    for (i = 0; i < len; i++)
    {
        XEP393FreeElement(ArrayGet(element->children, i));
    }

    if (element->parent && unlink)
    {
        XEP393Element *parent = element->parent;
        len = ArraySize(parent->children);
        for (i = 0; i < len; i++)
        {
            XEP393Element *c = ArrayGet(parent->children, i);
            if (c == element)
            {
                ArrayDelete(parent->children, i);
                break;
            }
        }
    }

    ArrayFree(element->children);
    Free(element->text_data);
    Free(element);
}
void
XEP393FreeElement(XEP393Element *element)
{
    XEP393FreeElementBase(element, false);
}

static StringRect
DecodeQuote(StringRect rect, size_t *skip)
{
    StringRect ret = StrFullRect(NULL);
    int lines = 0;

    /* C abuse of chaining operations */
    while ((StrGet(&rect, lines, 0) == '>') && ++lines)
    {
        if (!ret.source_lines)
        {
            int shift_by = 1, ch;
            ret = rect;
            ret.end_line--;

            /* TODO: You can easily craft strings that conceal data(
             * >           Please mind the whitespace
             * > hidden    we're concealing data to Matrix
             * > star in   Well, you can still stare at the body and XML 
             * > four      but that's for Nerds
             * > seasons   See, Touhou reference!
             * concealing!) */
            while ((ch = StrGet(&rect, lines - 1, shift_by)) && isspace(ch))
            {
                shift_by++;
            }

            ret = StrShift(ret, shift_by);
            continue;
        }
    }

    if (!lines)
    {
        return StrFullRect(NULL);
    }
    ret.end_line = ret.start_line + lines - 1;

    if (skip)
    {
        *skip = lines;
    }

    return ret;
}

static StringRect
DecodeSpan(StringRect rect, char del, size_t *skip)
{
    StringRect ret = StrFullRect(NULL);
    int chars = 0;
    char c;

    if (StrGet(&rect, 0, 0) != del)
    {
        return ret;
    }

    rect = StrShift(rect, 1);

    /* C abuse of chaining operations */
    while (((c = StrGet(&rect, 0, chars)) != del) && ++chars)
    {
        if (!c)
        {
            return StrFullRect(NULL);
        }
        if (!ret.source_lines && isspace(c))
        {
            return StrFullRect(NULL);
        }

        if (!ret.source_lines)
        {
            ret = rect;
            ret.end_char = ret.start_char;
            continue;
        }

        ret.end_char++;
    }
    ret.end_char++;

    if (!chars)
    {
        return StrFullRect(NULL);
    }

    {
        char *temp, *gen = NULL, chara[2] = { 0, '\0' };
        size_t i;
        for (i = 0; i < StrViewChars(ret, 0); i++)
        {
            *chara = StrGet(&ret, 0, i);
            if (!*chara)
            {
                break;
            }

            temp = gen;
            gen = StrConcat(2, gen, chara);
            Free(temp);
        }


        Free(gen);
    }

    if (skip)
    {
        *skip = chars;
    }

    return ret;
}

#define BLOCK_QUOTE (1 << 0)
#define BLOCK_CODES (1 << 1)
static void
ParseLine(XEP393Element *elem, StringRect line)
{
    XEP393Element *span_item, *line_item;
    StringRect shifted;
    size_t ch_idx, chars = StrViewChars(line, 0);
    size_t text_start = 0;
    size_t i;

    for (ch_idx = 0; ch_idx < chars; ch_idx++)
    {
        char curr = StrGet(&line, 0, ch_idx);
        StringRect span;
        shifted = line;
        shifted.start_char += ch_idx;

#define HandleSpan(del, sym) \
        if (curr == del &&  \
            (span = DecodeSpan(shifted, del, NULL)).source_lines) \
        { \
            size_t text_end = ch_idx; \
 \
            { \
                char *temp, *gen = NULL, chara[2] = { 0, '\0' }; \
                for (i = text_start; i < text_end; i++) \
                { \
                    *chara = StrGet(&line, 0, i); \
 \
                    temp = gen; \
                    gen = StrConcat(2, gen, chara); \
                    Free(temp); \
                } \
                line_item = CreateElementVessel(elem, XEP393_TEXT); \
                line_item->text_data = gen; \
            } \
 \
            span_item = CreateElementVessel(elem, sym); \
            ParseLine(span_item, span); \
            text_start = span.end_char - line.start_char + 1; \
            ch_idx = span.end_char; \
            continue; \
        }

        HandleSpan('*', XEP393_EMPH);
        HandleSpan('_', XEP393_ITALIC);
        HandleSpan('~', XEP393_SRKE);
        HandleSpan('`', XEP393_MONO);
        /* TODO: Can we troll and introduce | as a Parsee extension? */
    }

    {
        char *temp, *gen = NULL, chara[2] = { 0, '\0' };
        for (i = text_start; i < chars; i++)
        {
            *chara = StrGet(&line, 0, i);

            temp = gen;
            gen = StrConcat(2, gen, chara);
            Free(temp);
        }
        line_item = CreateElementVessel(elem, XEP393_TEXT);
        line_item->text_data = gen;
    }
}
static void
XEP393Parse(XEP393Element *root, StringRect region, int flags)
{
    size_t i, lines = StrViewLines(region);

    for (i = 0; i < lines; i++)
    {
        StringRect extend_line = StrGetl(&region, i, true);
        StringRect single_line = StrGetl(&region, i, false);
        size_t jump_by = 0;
        XEP393Element *sub;

        if ((flags & BLOCK_QUOTE) && (StrGet(&single_line, 0, 0) == '>'))
        {
            StringRect quote = DecodeQuote(extend_line, &jump_by);
            if (quote.source_lines)
            {
                sub = CreateElementVessel(root, XEP393_QUOT);
                XEP393Parse(sub, quote, flags);

                i += jump_by - 1;
                continue;
            }
        }
        /* TODO: Codeblocks, this shouldn't be too hard. */

        if (!(flags & BLOCK_CODES))
        {
            sub = CreateElementVessel(root, XEP393_LINE);
            ParseLine(sub, single_line);
            continue;
        }
    }
}

XEP393Element *
XEP393(char *message)
{
    char **lines = StrSplitLines(message);
    StringRect view = StrFullRect(lines);
    XEP393Element *root = CreateElementVessel(NULL, XEP393_ROOT);

    XEP393Parse(root, view, BLOCK_QUOTE);

    StrFreeLines(lines);
    return root;
}

#include <XML.h>

static void
ShoveXML(XEP393Element *element, XMLElement *xmlparent)
{
    XMLElement *head = xmlparent;
    size_t i;
    bool par = false;
    if (!element || !xmlparent)
    {
        return;
    }

    if (element->type == XEP393_CODE)
    {
        XMLElement *pre, *code, *text;
        pre = XMLCreateTag("pre");
        code = XMLCreateTag("code");
        text = XMLCreateText(element->text_data);
        XMLAddChild(code, text);
        XMLAddChild(pre, code);
        XMLAddChild(xmlparent, pre);
        return;
    }

    switch (element->type)
    {
        case XEP393_ITALIC:
            head = XMLCreateTag("i");
            XMLAddChild(xmlparent, head);
            XMLAddChild(head, XMLCreateText("_"));
            break;
        case XEP393_MONO:
            head = XMLCreateTag("code");
            XMLAddChild(xmlparent, head);
            XMLAddChild(head, XMLCreateText("`"));
            break;
        case XEP393_SRKE:
            head = XMLCreateTag("s");
            XMLAddChild(xmlparent, head);
            XMLAddChild(head, XMLCreateText("~"));
            break;
        case XEP393_EMPH:
            head = XMLCreateTag("strong");
            XMLAddChild(xmlparent, head);
            XMLAddChild(head, XMLCreateText("*"));
            break;
        case XEP393_LINE:
            head = XMLCreateTag("p");
            XMLAddChild(xmlparent, head);
            par = true;
            break;
        case XEP393_QUOT:
            head = XMLCreateTag("blockquote");
            XMLAddChild(xmlparent, head);
            break;
        default: break;
    }
    if (ArraySize(element->children) == 0 && 
        element->text_data)
    {
        XMLElement *text = XMLCreateText(element->text_data);
        XMLAddChild(head, text);
    }

    for (i = 0; i < ArraySize(element->children); i++)
    {
        XEP393Element *sub = ArrayGet(element->children, i);
        ShoveXML(sub, head);
    }

    switch (element->type)
    {
        case XEP393_ITALIC:
            XMLAddChild(head, XMLCreateText("_"));
            break;
        case XEP393_MONO:
            XMLAddChild(head, XMLCreateText("`"));
            break;
        case XEP393_SRKE:
            XMLAddChild(head, XMLCreateText("~"));
            break;
        case XEP393_EMPH:
            XMLAddChild(head, XMLCreateText("*"));
            break;
        default: break;
    }

    /* NOTE: Hack to get rid of stranded <p/>-tags with no 
     * children. */
    if (par && ArraySize(head->children) == 0)
    {
        ArrayDelete(
            xmlparent->children,
            ArraySize(xmlparent->children) - 1
        );
        XMLFreeElement(head);
    }
}

#include <StringStream.h>
char *
XEP393ToXMLString(XEP393Element *xepd)
{
    XMLElement *root;

    Stream *writer;
    char *ret = NULL;
    if (!xepd)
    {
        return NULL;
    }

    root = XMLCreateTag("span");
    ShoveXML(xepd, root);

    writer = StrStreamWriter(&ret);
    XMLEncode(writer, root);
    XMLFreeElement(root);
    StreamFlush(writer);
    StreamClose(writer);

    return ret;
}