!> Logging module for S3 accessor library.
!>
!> Provides configurable logging with multiple severity levels to help
!> diagnose issues and understand library behavior.
!>
!> ## Log Levels
!>
!> - **NONE (0)**: No logging output
!> - **ERROR (1)**: Critical errors only
!> - **WARN (2)**: Warnings and errors
!> - **INFO (3)**: General information, warnings, and errors
!> - **DEBUG (4)**: Detailed debugging information
!> - **TRACE (5)**: Very detailed tracing (includes curl commands, responses)
!>
!> ## Usage
!>
!> ```fortran
!> use s3_logger
!>
!> ! Set log level (default is ERROR)
!> call s3_set_log_level(S3_LOG_LEVEL_DEBUG)
!>
!> ! Log messages at different levels
!> call s3_log_error('Failed to download object')
!> call s3_log_warn('Retrying connection')
!> call s3_log_info('Initialized S3 connection')
!> call s3_log_debug('Built URL: https://...')
!> call s3_log_trace('curl command: curl -s ...')
!> ```
!>
!> ## Environment Variable
!>
!> Log level can be set via environment variable `S3_LOG_LEVEL`:
!> ```bash
!> export S3_LOG_LEVEL=DEBUG
!> ./my_program
!> ```
!>
!> Valid values: NONE, ERROR, WARN, INFO, DEBUG, TRACE (case-insensitive)
module s3_logger
implicit none
private
! Public procedures
public :: s3_set_log_level
public :: s3_get_log_level
public :: s3_log_error
public :: s3_log_warn
public :: s3_log_info
public :: s3_log_debug
public :: s3_log_trace
public :: s3_init_logger
! Log level constants (public)
integer, parameter, public :: S3_LOG_LEVEL_NONE = 0
integer, parameter, public :: S3_LOG_LEVEL_ERROR = 1
integer, parameter, public :: S3_LOG_LEVEL_WARN = 2
integer, parameter, public :: S3_LOG_LEVEL_INFO = 3
integer, parameter, public :: S3_LOG_LEVEL_DEBUG = 4
integer, parameter, public :: S3_LOG_LEVEL_TRACE = 5
! Current log level (default ERROR)
integer, save :: current_log_level = S3_LOG_LEVEL_ERROR
contains
!> Initialize logger from environment variable.
!>
!> Reads S3_LOG_LEVEL environment variable and sets log level accordingly.
!> If not set or invalid, defaults to ERROR level.
!>
!> Called automatically by s3_init(), but can be called manually.
subroutine s3_init_logger()
character(len=256) :: env_value
integer :: status
call get_environment_variable('S3_LOG_LEVEL', env_value, status=status)
if (status == 0 .and. len_trim(env_value) > 0) then
call parse_log_level(trim(env_value), current_log_level)
end if
end subroutine s3_init_logger
!> Set the current log level.
!>
!> @param[in] level Log level (S3_LOG_LEVEL_NONE to S3_LOG_LEVEL_TRACE)
subroutine s3_set_log_level(level)
integer, intent(in) :: level
if (level >= S3_LOG_LEVEL_NONE .and. level <= S3_LOG_LEVEL_TRACE) then
current_log_level = level
end if
end subroutine s3_set_log_level
!> Get the current log level.
!>
!> @return Current log level
function s3_get_log_level() result(level)
integer :: level
level = current_log_level
end function s3_get_log_level
!> Log an error message.
!>
!> @param[in] message Error message to log
subroutine s3_log_error(message)
character(len=*), intent(in) :: message
if (current_log_level >= S3_LOG_LEVEL_ERROR) then
write(*, '(A,A)') '[S3 ERROR] ', trim(message)
end if
end subroutine s3_log_error
!> Log a warning message.
!>
!> @param[in] message Warning message to log
subroutine s3_log_warn(message)
character(len=*), intent(in) :: message
if (current_log_level >= S3_LOG_LEVEL_WARN) then
write(*, '(A,A)') '[S3 WARN] ', trim(message)
end if
end subroutine s3_log_warn
!> Log an informational message.
!>
!> @param[in] message Info message to log
subroutine s3_log_info(message)
character(len=*), intent(in) :: message
if (current_log_level >= S3_LOG_LEVEL_INFO) then
write(*, '(A,A)') '[S3 INFO] ', trim(message)
end if
end subroutine s3_log_info
!> Log a debug message.
!>
!> @param[in] message Debug message to log
subroutine s3_log_debug(message)
character(len=*), intent(in) :: message
if (current_log_level >= S3_LOG_LEVEL_DEBUG) then
write(*, '(A,A)') '[S3 DEBUG] ', trim(message)
end if
end subroutine s3_log_debug
!> Log a trace message (very detailed).
!>
!> @param[in] message Trace message to log
subroutine s3_log_trace(message)
character(len=*), intent(in) :: message
if (current_log_level >= S3_LOG_LEVEL_TRACE) then
write(*, '(A,A)') '[S3 TRACE] ', trim(message)
end if
end subroutine s3_log_trace
!> Parse log level from string.
!>
!> @param[in] level_str Log level as string (NONE, ERROR, WARN, INFO, DEBUG, TRACE)
!> @param[out] level Parsed log level constant
subroutine parse_log_level(level_str, level)
character(len=*), intent(in) :: level_str
integer, intent(out) :: level
character(len=256) :: upper_str
integer :: i
! Convert to uppercase
upper_str = level_str
do i = 1, len_trim(upper_str)
if (upper_str(i:i) >= 'a' .and. upper_str(i:i) <= 'z') then
upper_str(i:i) = char(ichar(upper_str(i:i)) - 32)
end if
end do
select case (trim(upper_str))
case ('NONE', '0')
level = S3_LOG_LEVEL_NONE
case ('ERROR', '1')
level = S3_LOG_LEVEL_ERROR
case ('WARN', 'WARNING', '2')
level = S3_LOG_LEVEL_WARN
case ('INFO', '3')
level = S3_LOG_LEVEL_INFO
case ('DEBUG', '4')
level = S3_LOG_LEVEL_DEBUG
case ('TRACE', '5')
level = S3_LOG_LEVEL_TRACE
case default
level = S3_LOG_LEVEL_ERROR ! Default to ERROR
write(*, '(A,A,A)') '[S3 WARN] Unknown log level "', trim(level_str), &
'", defaulting to ERROR'
end select
end subroutine parse_log_level
end module s3_logger
