# From configuration
# root   Directory which files reside in.

namespace eval http {

    # server        channel address port
    # Server process
    #
    # content-type  filename
    # Find the MIME content type of a file
    #
    # send-file     channel filename
    # Open and send a file.
    #
    # respond       channel status ?optional
    # Makes HTTP response with status on channel. Optional is an optional argument with various meanings.
    #
    # error-page    status
    # Returns a small error page.

    variable status_codes            \
		[dict create                 \
			 200 {OK}                \
			 301 {Moved Permanently} \
			 400 {Bad Request}       \
			 404 {Not Found}         \
			]

    variable mime_types              \
		[dict create                 \
			 .txt  text/plain        \
			 .html text/html         \
			 .css  text/css          \
			 {}    text/html         \
			 .png  image/png         \
			 .jpg  image/jpeg        \
			 .ttf  font/ttf          \
			 .pdf  application/pdf   \
			 .mp3  audio/mpeg        \
			]
    
    proc server {channel address port} {
		variable hook_namespace;
		variable root;
		
		## (1) Handle first line
		puts "(1)"
		
		gets $channel line
		set request_target [request_target::get $channel $line]

		## (2) Get rest of packet.
		set packet {}
		while { [gets $channel line] } {
			puts $line
			## Check if field-line is in correct form.
			##                ^field-name  :     OWS         field-value OWS         $
			if [expr ![regexp {^[[:alpha:]-]+(:){1}[[:space:]]?[[:print:]]+[[:space:]]?$} $line]] {
				respond $channel 400
			}

			

			## Reject duplicates of the host field.
			set key [string tolower [string range $line 0 [expr [string first : $line] - 1]]]
			if [expr ([string compare $key "host"] == 0) && ([lsearch $packet "host"] != -1)] {
				respond $channel 400
			}
			## Add to packet dictionary
			dict append packet \
				[string tolower [string range $line 0 [expr [string first : $line] - 1]]] \
				[string range $line [expr [string first : $line] + 2] end]
		}
		
		## Reject packets that have no host field.
		if {[lsearch [dict keys $packet] "host"] == -1} {
			respond $channel 400
		}

		
		## (3) Find if the file exists, or there is a hooked application.
		# If file exists, then 200 OK!
		set filename [string cat $root [request_target::file $request_target]]
		if [expr [file exists $filename] && [file isfile $filename]] {
			respond $channel 200 $filename	
		} elseif [expr [file exists [string cat $filename "index.html"]] && [file isfile [string cat $filename "index.html"]]] {
			respond $channel 200 [string cat $filename "index.html"]
		}
		#TODO: Make some filler for this.
		# If it's one of the targets of the imported namespace, then 200 OK!
		#elseif [namespace eval $hook_namespace [string cat {lsearch $targets } "$filename"]] {
		#	respond $channel 200 $filename
		#}

		## Otherwise, 404.
		respond $channel 404
    }
    
    proc content-type {filename} {
		variable mime_types;
		return [dict get $mime_types [file extension $filename]]		
	}

	# Sends an opened file or cached file.
	proc send-file {channel filename} {
		#TODO: configure it to try the cache.
		#TODO: configure channels to use binary translation if content type is not text/*
		set file [open $filename]
		fconfigure $file    -translation binary
		fconfigure $channel -translation binary
		fcopy $file $channel
		close $file
	}
	
	## Header
	## optional stands for a few different values.
	##  200 : Request Target
	##  3xx : Location
	proc respond {channel status {optional {}}} {

		## Import Variables
		variable root;
		variable status_codes;
		variable hook_namespace;
		## New Variables
		variable content {};
		variable response {};
		
		## If it's not a status code we know, then error, it's your fault!
		if [expr [lsearch [dict keys $status_codes] $status] == -1] {
			error "Invalid status response"
		}
		
		## (1) Give Status Line
		append response "HTTP/1.1 $status [dict get $status_codes $status]\n"
		append response "Server: unknown\n"
		#append response "Last-Modified: Sun, 14 Apr 2024 01:58:24 GMT\n"
		append response "Date: [clock format [clock seconds] -format {%a, %d %b %Y %T GMT} -gmt 1]\n"
		
		if { $status == 200 } {
			if [file exists $optional] {
				append response "Content-Length: [file size $optional]\n"		
				append response "Content-Type: [content-type $optional]\n"
				append response "\n"
				puts -nonewline $channel $response
				send-file $channel $optional
			} else {
				#TODO: implement this when have something to implement!
				set content "Sup mate!"
				append response "Content-Length: [string bytelength $content]\n"
				append response "Content-Type: text/html\n"
				append response "\n"
				puts -nonewline $channel $response
				puts -nonewline $channel $content
			}
			# give a Last-Modified: field
			puts -nonewline $channel $response
		} else {
			## Error Page
			set content [error-page $status]
			append response "Content-Type: text/html\n"
			append response "Content-Length: [string bytelength $content]\n"
			if [expr ($status >= 300) && ($status <= 308) && ([string compare $optional {}] != 0)] {
				append response "Location: $optional\n"
			}
			append response "\n"
			puts -nonewline $channel $response
			puts -nonewline $channel $content
		}
		close $channel
		return -level 2
	}


	proc error-page {status {location {}}} {
		variable status_codes
		return "<html><head><title>Status: $status</title></head><body style='font-size:48px;text-align:center'><b style='font-size:72px'>$status</b><br>[dict get $status_codes $status]</body></html>"
	}
	
	
	source http-request_target.tcl
}