#include "oslib.h"
#include <errno.h>

static int OS_LoadFileHandle(OSFileHandle *hand) {
    int err;
    int ref;
    UInt32 sz;
    void *buffer;

    hand->loaded = 0;

    err = OS_Open(&hand->spec, OSReadOnly, &ref);
    if (!err) {
        err = OS_GetSize(ref, &sz);
        if (!err) {
            err = OS_ResizeHandle(&hand->hand, sz);
            if (!err) {
                buffer = OS_LockHandle(&hand->hand);
                err = OS_Read(ref, buffer, &sz);
                if (!err) {
                    hand->loaded = 1;
                    hand->changed = 0;
                }
                OS_UnlockHandle(&hand->hand);
            }
        }
        OS_Close(ref);
    }

    return err;
}

static int OS_WriteFileHandle(OSFileHandle *hand) {
    int err;
    int ref;
    UInt32 sz;
    void *buffer;

    if (!hand->loaded && !hand->changed)
        return 0;

    OS_Delete(&hand->spec);
    err = OS_Create(&hand->spec, &OS_TEXTTYPE);
    if (!err) {
        err = OS_Open(&hand->spec, OSReadWrite, &ref);
        if (!err) {
            err = OS_GetHandleSize(&hand->hand, &sz);
            if (!err) {
                buffer = OS_LockHandle(&hand->hand);
                err = OS_Write(ref, buffer, &sz);
                if (!err)
                    hand->changed = 0;
                OS_UnlockHandle(&hand->hand);
                OS_Close(ref);
            }
        }
    }

    return err;
}

int OS_NewFileHandle(const OSSpec *spec, OSHandle *src, Boolean writeable, OSFileHandle *hand) {
    int err;

    if (!writeable && src)
        return EACCES;

    hand->spec = *spec;
    hand->writeable = writeable;

    if (!src) {
        err = OS_NewHandle(0, &hand->hand);
        if (err)
            return err;
        err = OS_LoadFileHandle(hand);
    } else {
        err = OS_CopyHandle(src, &hand->hand);
        if (err)
            return err;
        hand->changed = 1;
        hand->loaded = 1;
    }

    return err;
}

int OS_LockFileHandle(OSFileHandle *hand, Ptr *ptr, UInt32 *size) {
    *size = 0;

    if (!OS_ValidHandle(&hand->hand))
        return ENOMEM;

    *ptr = OS_LockHandle(&hand->hand);
    OS_GetHandleSize(&hand->hand, size);
    return 0;
}

int OS_UnlockFileHandle(OSFileHandle *hand) {
    if (!OS_ValidHandle(&hand->hand))
        return ENOMEM;

    OS_UnlockHandle(&hand->hand);
    return 0;
}

int OS_FreeFileHandle(OSFileHandle *hand) {
    int err;

    if (hand->writeable && hand->changed) {
        err = OS_WriteFileHandle(hand);
        if (err)
            return err;
    }

    if (!OS_ValidHandle(&hand->hand))
        return ENOMEM;

    err = OS_FreeHandle(&hand->hand);
    if (err)
        return err;

    hand->loaded = 0;
    return 0;
}

void OS_GetFileHandleSpec(const OSFileHandle *hand, OSSpec *spec) {
    *spec = hand->spec;
}