#ifndef VTR_LOG_H
#define VTR_LOG_H
#include <tuple>

/*
 * This header defines useful logging macros for VTR projects.
 *
 * Message Type
 * ============
 *
 * Three types of log message types are defined:
 *      VTR_LOG         - The standard 'info' type log message
 *      VTR_LOG_WARN    - A warning log message
 *      VTR_LOG_ERROR   - An error log message
 * 
 * For example:
 *
 *      VTR_LOG("This produces a regular '%s' message\n", "info");
 *      VTR_LOG_WARN("This produces a '%s' message\n", "warning");
 *      VTR_LOG_ERROR("This produces an '%s' message\n", "error");
 *
 * Conditional Logging
 * ===================
 *
 * Each of the three message types also have a VTR_LOGV_* variant,
 * which will cause the message to be logged if a user-defined condition
 * is satisifed.
 *
 * For example:
 *
 *      VTR_LOGV(verbosity > 5, "This message will be logged only if verbosity is greater than %d\n", 5);
 *      VTR_LOGV_WARN(verbose, "This warning message will be logged if verbose is true\n");
 *      VTR_LOGV_ERROR(false, "This error message will never be logged\n");
 *
 * Custom Location Logging
 * =======================
 *
 * Each of the three message types also have a VTR_LOGF_* variant,
 * which will cause the message to be logged for a custom file and
 * line loation.
 *
 * For example:
 *
 *      VTR_LOGF("my_file.txt", 42 "This message will be logged from file 'my_file.txt' line %d\n", 42);
 *  
 * Debug Logging
 * =============
 *
 * For debug purposes it may be useful to have additional logging.
 * This is supported by VTR_LOG_DEBUG() and VTR_LOGV_DEBUG().
 *
 * To avoid run-time overhead, these are only enabled if VTR_ENABLE_DEBUG_LOGGING 
 * is defined (disabled by default).
 */

//Unconditional logging macros
#define VTR_LOG(...) VTR_LOGV(true, __VA_ARGS__)
#define VTR_LOG_WARN(...) VTR_LOGV_WARN(true, __VA_ARGS__)
#define VTR_LOG_ERROR(...) VTR_LOGV_ERROR(true, __VA_ARGS__)
#define VTR_LOG_NOP(...) VTR_LOGV_NOP(true, __VA_ARGS__)

//Conditional logging macros
#define VTR_LOGV(expr, ...) VTR_LOGVF(expr, __FILE__, __LINE__, __VA_ARGS__)
#define VTR_LOGV_WARN(expr, ...) VTR_LOGVF_WARN(expr, __FILE__, __LINE__, __VA_ARGS__)
#define VTR_LOGV_ERROR(expr, ...) VTR_LOGVF_ERROR(expr, __FILE__, __LINE__, __VA_ARGS__)
#define VTR_LOGV_NOP(expr, ...) VTR_LOGVF_NOP(expr, __FILE__, __LINE__, __VA_ARGS__)

//Custom file-line location logging macros
#define VTR_LOGF(file, line, ...) VTR_LOGVF(true, file, line, __VA_ARGS__)
#define VTR_LOGF_WARN(file, line, ...) VTR_LOGVF_WARN(true, file, line, __VA_ARGS__)
#define VTR_LOGF_ERROR(file, line, ...) VTR_LOGVF_ERROR(true, file, line, __VA_ARGS__)
#define VTR_LOGF_NOP(file, line, ...) VTR_LOGVF_NOP(true, file, line, __VA_ARGS__)

//Conditional logging and custom file-line location macros
#define VTR_LOGVF(expr, file, line, ...) \
    do { \
        if (expr) vtr::printf(__VA_ARGS__); \
    } while (false)

#define VTR_LOGVF_WARN(expr, file, line, ...) \
    do { \
        if (expr) vtr::printf_warning(file, line, __VA_ARGS__); \
    } while (false)

#define VTR_LOGVF_ERROR(expr, file, line, ...) \
    do { \
        if (expr) vtr::printf_error(file, line, __VA_ARGS__); \
    } while (false)

//No-op version of logging macro which avoids unused parameter warnings.
//
//Note that to avoid unused parameter warnings we call sizeof() and cast
//the result to void. sizeof is evaluated at compile time so there is no
//run-time overhead.
//
//Also note the use of std::make_tuple to ensure all arguments in VA_ARGS
//are used.
#define VTR_LOGVF_NOP(expr, file, line, ...) \
    do { \
        static_cast<void>(sizeof(expr)); \
        static_cast<void>(sizeof(file)); \
        static_cast<void>(sizeof(line)); \
        static_cast<void>(sizeof(std::make_tuple(__VA_ARGS__))); \
    } while (false)

//Debug logging macros
#ifdef VTR_ENABLE_DEBUG_LOGGING //Enable
# define VTR_LOG_DEBUG(...) VTR_LOG(__VA_ARGS__)
# define VTR_LOGV_DEBUG(expr, ...) VTR_LOGV(expr, __VA_ARGS__)
#else //Disable
# define VTR_LOG_DEBUG(...) VTR_LOG_NOP(__VA_ARGS__)
# define VTR_LOGV_DEBUG(expr, ...) VTR_LOGV_NOP(expr, __VA_ARGS__)
#endif

namespace vtr {

typedef void (*PrintHandlerInfo)(const char* pszMessage, ... );
typedef void (*PrintHandlerWarning)(const char* pszFileName, unsigned int lineNum, const char* pszMessage,	... );
typedef void (*PrintHandlerError)(const char* pszFileName, unsigned int lineNum, const char* pszMessage,	... );
typedef void (*PrintHandlerDirect)(const char* pszMessage,	... );

extern PrintHandlerInfo printf; //Same as printf_info
extern PrintHandlerInfo printf_info;
extern PrintHandlerWarning printf_warning;
extern PrintHandlerError printf_error;
extern PrintHandlerDirect printf_direct;

void set_log_file(const char* filename);

} //namespace


#endif