// uiAttributedString represents a string of UTF-8 text that can
// optionally be embellished with formatting attributes. libui
// provides the list of formatting attributes, which cover common
// formatting traits like boldface and color as well as advanced
// typographical features provided by OpenType like superscripts
// and small caps. These attributes can be combined in a variety of
// ways.
//
// Attributes are applied to runs of Unicode codepoints in the string.
// Zero-length runs are elided. Consecutive runs that have the same
// attribute type and value are merged. Each attribute is independent
// of each other attribute; overlapping attributes of different types
// do not split each other apart, but different values of the same
// attribute type do.
//
// The empty string can also be represented by uiAttributedString,
// but because of the no-zero-length-attribute rule, it will not have
// attributes.
//
// TODO note here about attribute ownership
//
// In addition, uiAttributedString provides facilities for moving
// between grapheme clusters, which represent a character
// from the point of view of the end user. The cursor of a text editor
// is always placed on a grapheme boundary, so you can use these
// features to move the cursor left or right by one "character".
// TODO does uiAttributedString itself need this
//
// uiAttributedString does not provide enough information to be able
// to draw itself onto a uiDrawContext or respond to user actions.
// In order to do that, you'll need to use a uiDrawTextLayout, which
// is built from the combination of a uiAttributedString and a set of
// layout-specific properties.
typedef struct uiAttributedString uiAttributedString;

// uiAttributedStringForEachAttributeFunc is the type of the function
// invoked by uiAttributedStringForEachAttribute() for every
// attribute in s. Refer to that function's documentation for more
// details.
typedef uiForEach (*uiAttributedStringForEachAttributeFunc)(const uiAttributedString *s, const uiAttributeSpec *spec, size_t start, size_t end, void *data);

// @role uiAttributedString constructor
// uiNewAttributedString() creates a new uiAttributedString from
// initialString. The string will be entirely unattributed.
_UI_EXTERN uiAttributedString *uiNewAttributedString(const char *initialString);

// @role uiAttributedString destructor
// uiFreeAttributedString() destroys the uiAttributedString s.
// TODO note here about attribute ownership
_UI_EXTERN void uiFreeAttributedString(uiAttributedString *s);

// uiAttributedStringString() returns the textual content of s as a
// '\0'-terminated UTF-8 string. The returned pointer is valid until
// the next change to the textual content of s.
_UI_EXTERN const char *uiAttributedStringString(const uiAttributedString *s);

// uiAttributedStringLength() returns the number of UTF-8 bytes in
// the textual content of s, excluding the terminating '\0'.
_UI_EXTERN size_t uiAttributedStringLen(const uiAttributedString *s);

// uiAttributedStringAppendUnattributed() adds the '\0'-terminated
// UTF-8 string str to the end of s. The new substring will be
// unattributed.
_UI_EXTERN void uiAttributedStringAppendUnattributed(uiAttributedString *s, const char *str);

// uiAttributedStringInsertAtUnattributed() adds the '\0'-terminated
// UTF-8 string str to s at the byte position specified by at. The new
// substring will be unattributed; existing attributes will be moved
// along with its text.
_UI_EXTERN void uiAttributedStringInsertAtUnattributed(uiAttributedString *s, const char *str, size_t at);

// TODO add the Append and InsertAtExtendingAttributes functions
// TODO and add functions that take a string + length

// uiAttributedStringDelete() deletes the characters and attributes of
// s in the range [start, end).
_UI_EXTERN void uiAttributedStringDelete(uiAttributedString *s, size_t start, size_t end);

// TODO const correct this somehow (the implementation needs to mutate the structure)
_UI_EXTERN size_t uiAttributedStringNumGraphemes(uiAttributedString *s);

// TODO const correct this somehow (the implementation needs to mutate the structure)
_UI_EXTERN size_t uiAttributedStringByteIndexToGrapheme(uiAttributedString *s, size_t pos);

// TODO const correct this somehow (the implementation needs to mutate the structure)
_UI_EXTERN size_t uiAttributedStringGraphemeToByteIndex(uiAttributedString *s, size_t pos);

_UI_EXTERN void uiAttributedStringSetAttribute(uiAttributedString *s, uiAttributeSpec *spec, size_t start, size_t end);

// TODO document this
// TODO possibly copy the spec each time to ensure it doesn't get clobbered
_UI_EXTERN void uiAttributedStringForEachAttribute(uiAttributedString *s, uiAttributedStringForEachAttributeFunc f, void *data);