function initialize_log, name_string

;+
;$Log:
;
; NAME:
;   initialize_log
;
; PURPOSE:
;   Creates a log file and writes a message to indicate the start of the log file
;
; CATEGORY:
;   AMIE Calibration - part of the project 'amie_pipeline'
;
; CALLING SEQUENCE:
;   logname = initialize_log (name_string)
;
; INPUTS:
;   name_string: string message created by the program to be inserted in the log file
;   the current date is then appended to the name
;
; OUTPUTS:
;    log file name for use in the create log entries module
;    log file of the AMIE pipeline
;
; COMMON BLOCKS:
;   None.
;
; SIDE EFFECTS:
;   Hopefully none.
;
; RESTRICTIONS:
;   The log file must be started with the start keyword at the beginning of the program.
;
; MODIFICATION HISTORY:
;   2004 Feb 16, MA: First version
;
; (c) 2004, Miguel Almeida, ESA/RSSD
;-

;-------------------------------------------------------------------------------------------------------------------------
;
;Create log file on disk with time of creation in the file name
;
;-------------------------------------------------------------------------------------------------------------------------

;-------------------------------------------------------------------------------------------------------------------------
;retrieve the date and time from the system in UTC and put it in the format YYYYMonDD_HHhMMmSSs
date_time = string(FORMAT='(C(CYI,CMoA,CDI2.2,"_",CHI2.2, "h",  CMI2.2,"m", CSI2.2,"s"))',SYSTIME(/julian,/utc))
;-------------------------------------------------------------------------------------------------------------------------

;-------------------------------------------------------------------------------------------------------------------------
;create the log file name with the name string that is input to the initialize log procedure and the string of
;the log file creation date and time
filename_string = name_string + date_time + '.log'
;-------------------------------------------------------------------------------------------------------------------------

openw, log_unit, filename_string, /get_lun

;-------------------------------------------------------------------------------------------------------------------------
;put two entries in the log file flagging the pipeline initialization and the creation of the log file
printf, log_unit, '['+date_time+' UT] ' + '[INITIALIZE LOG] AMIE Pipeline initialized '
printf, log_unit, '['+date_time+' UT] [INITIALIZE LOG] ' + filename_string + ' created'
;-------------------------------------------------------------------------------------------------------------------------

close, log_unit
free_lun, log_unit

;-------------------------------------------------------------------------------------------------------------------------
;
;Returns the log name to the main program in order to be possible for the rest of the modules to create entries
;
;-------------------------------------------------------------------------------------------------------------------------

logname = filename_string
return, logname

end