#include <XEP393.h>

#include <Cytoplasm/Memory.h>
#include <Cytoplasm/Array.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);
}

typedef struct StrView {
    char *start;
    char *end;

    bool heap_free;
} StrView;
#define ViewLength(v) ((size_t) ((v.end) - (v.start)))
static char *
StringifyView(StrView v)
{
    char *r;
    size_t len;
    if (!v.start || v.start > v.end)
    {
        return NULL;
    }

    len = ViewLength(v);
    r = Malloc(len + 1);
    memcpy(r, v.start, len);
    r[len] = '\0';

    return r;
}
static StrView 
CreateStaticView(char *str)
{
    StrView view = {
        .start = str,
        .end = str + strlen(str),
        .heap_free = false
    };

    return view;
}
static bool
IdentifySpan(char span_tag, StrView in, StrView *view)
{
    size_t length;
    bool found = false;
    char prev = '\0';
    if (in.start >= in.end)
    {
        return false;
    }
    if (ViewLength(in) < 2)
    {
        return false;
    }

    if (*in.start != span_tag || isspace(*(in.start + 1)))
    {
        /* The opening styling directive MUST NOT be followed  
         * by a whitespace character */
        return false;
    }
    view->start = in.start + 1;
    in.start += 1;

    for (length = 0; ViewLength(in) > 0; length++, in.start++)
    {
        if (*in.start == span_tag)
        {
            found = true;
            break;
        }

        prev = *in.start;
    }
    if (!found || !length || (prev && isspace(prev)))
    {
        /* the closing styling directive MUST NOT be preceeded 
         * by a whitespace character. */
        return false;
    }

    view->end = in.start;
    return true;
}


static void
XEP393Decode(StrView view, XEP393Element *root)
{
    StrView subview = view;
    StrView textview = view;
    XEP393Element *text, *span;
    bool managed = false;
    char prev = '\0', curr = '\0';

    textview.end = subview.start;
    for (; subview.start < subview.end; subview.start++)
    {
        StrView span_view;
        managed = false;
        curr = *subview.start;
        if (prev == '\0' || prev == '\n')
        {
            /* TODO: Start of line, start parsing blocks. */
        }
#define Spanify(xep_symbol) \
            managed = true; \
            textview.end = subview.start; \
            text = CreateElementVessel( \
                root, XEP393_TEXT \
            ); \
            text->text_data = StringifyView(textview); \
            \
            /* Found a span. */ \
            span = CreateElementVessel( \
                root, xep_symbol \
            ); \
            \
            XEP393Decode(span_view, span); \
            \
            /* Update subview */ \
            subview.start = span_view.end + 1; \
            \
            /* Update textview */ \
            textview.start = subview.start; \
            textview.end = subview.start
        if (IdentifySpan('_', subview, &span_view))
        {
            Spanify(XEP393_ITALIC);
        }
        else if (IdentifySpan('*', subview, &span_view))
        {
            Spanify(XEP393_EMPH);
        }
        else if (IdentifySpan('`', subview, &span_view))
        {
            Spanify(XEP393_MONO);
        }
        else
        {
            /* Text character: update end */
            textview.end = subview.start;
        }

        prev = curr;
    }

    if (!managed)
    {
        textview.end = subview.start;
        text = CreateElementVessel(
            root, XEP393_TEXT
        );
        text->text_data = StringifyView(textview);
    }
}

XEP393Element *
XEP393(char *message)
{
    StrView view = CreateStaticView(message);
    XEP393Element *root = CreateElementVessel(NULL, XEP393_ROOT);

    /* TODO: Parse blocks first, *then* spans. Considering the 
     * current architecture, this shouldn't be too hard to integrate,
     * given how string views already manage boundaries, and elements 
     * can already be used to contain blocks I think. 
     *
     * Actually, nevermind, these would be pure pain. Nested blocks, 
     * unterminated ones, QUOTES. Just hell. I hate parsing this shit. */
    XEP393Decode(view, root);
    return root;
}

#include <XML.h>

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

    switch (element->type)
    {
        case XEP393_ITALIC:
            head = XMLCreateTag("i");
            XMLAddChild(xmlparent, head);
            break;
        case XEP393_EMPH:
            head = XMLCreateTag("strong");
            XMLAddChild(xmlparent, head);
            break;
        case XEP393_MONO:
            head = XMLCreateTag("code");
            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);
    }
}

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

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

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

    writer = StrStreamWriter(&ret);
    for (i = 0; i < ArraySize(root->children); i++)
    {
        XMLEncode(writer, ArrayGet(root->children, i));
    }
    XMLFreeElement(root);
    StreamFlush(writer);
    StreamClose(writer);

    return ret;
}