(define-module (inkplate)
  #:use-module ((ice-9 format) #:select (format))
  #:use-module ((srfi srfi-9) #:select (define-record-type))
  #:use-module ((termios system) #:select (termios-B115200))
  #:use-module ((termios with-exceptions)
                #:select (make-termios-struct
                          tc-get-attr!
                          tc-set-attr
                          cf-make-raw!
                          cf-set-speed!))

  #:export (<inkplate>
            make-inkplate
            inkplate?
            inkplate-input-port
            inkplate-output-port

            convert-string-to-hex

            open
            close
            echo
            draw-pixel
            draw-line
            draw-fast-vertical-line
            draw-fast-horizontal-line
            draw-rectangle
            draw-circle
            draw-triangle
            draw-rounded-rectangle
            fill-rectangle
            fill-circle
            fill-triangle
            fill-rounded-rectangle
            print
            set-text-size
            set-cursor
            set-text-wrap
            set-rotation
            draw-bitmap
            set-display-mode
            get-display-mode
            clear-screen
            update
            partial-update
            read-temperature
            read-touchpad
            read-battery
            panel-supply
            get-panel-state
            draw-image
            draw-thick-line
            draw-ellipse
            fill-ellipse
            send))

(define-record-type <inkplate>
  (make-inkplate input-port output-port)
  inkplate?
  (input-port inkplate-input-port)
  (output-port inkplate-output-port))

(define (convert-string-to-hex string)
  "Convert STRING to a hexadecimal representation of the text."
  (string-join
   (map (lambda (x) (format #f "~2,'0x" (char->integer x)))
        (string->list string))
   ""))

(define (open device-path)
  "Open a connection to an Inkplate on the named DEVICE-PATH."
  (let ((port (open-file device-path "r+"))
        (termios (make-termios-struct)))
    (tc-get-attr! port termios)
    (cf-make-raw! termios)
    (cf-set-speed! termios termios-B115200)
    (tc-set-attr port termios)
    (make-inkplate port port)))

(define (close device)
  "Close a connection to an Inkplate in DEVICE."
  (close-port (inkplate-output-port device))
  (close-port (inkplate-input-port device)))

(define (echo device)
  "Send a command to check if the DEVICE is receiving commands."
  (display "#?*" (inkplate-output-port device)))

(define (draw-pixel device x y color)
  "Draw a pixel on DEVICE at coordinates X and Y in COLOR."
  (format (inkplate-output-port device) "#0(~3,'0d,~3,'0d,~2,'0d)*" x y color))

(define (draw-line device x1 y1 x2 y2 color)
  "Draw a line on DEVICE from coordinates X1,Y1 to X2,Y2 in COLOR."
  (format (inkplate-output-port device)
          "#1(~3,'0d,~3,'0d,~3,'0d,~3,'0d,~2,'0d)*" x1 y1 x2 y2 color))

(define (draw-fast-vertical-line device x y length color)
  "Draw a vertical line on DEVICE from X,Y for LENGTH pixels in COLOR."
  (format (inkplate-output-port device)
          "#2(~3,'0d,~3,'0d,~3,'0d,~2,'0d)*" x y length color))

(define (draw-fast-horizontal-line device x y length color)
  "Draw a horizontal line on DEVICE from X,Y for LENGTH pixels in COLOR."
  (format (inkplate-output-port device)
          "#3(~3,'0d,~3,'0d,~3,'0d,~2,'0d)*" x y length color))

(define (draw-rectangle device x y width height color)
  "Draw a rectangle on DEVICE at X,Y WIDTH wide by HEIGHT high in COLOR.
This function draws an outline of a rectangle whereas ‘fill-rectangle’ fills the
rectangle with the specified color."
  (format (inkplate-output-port device)
          "#4(~3,'0d,~3,'0d,~3,'0d,~3,'0d,~2,'0d)*" x y width height color))

(define (draw-circle device x y radius color)
  "Draw a circle on DEVICE at X,Y with RADIUS in COLOR.
This function draws an outline of a circle whereas ‘fill-circle’ fills the
circle with the specified color."
  (format (inkplate-output-port device)
          "#5(~3,'0d,~3,'0d,~3,'0d,~2,'0d)*" x y radius color))

(define (draw-triangle device x1 y1 x2 y2 x3 y3 color)
  "Draw a triangle on DEVICE at points X1,Y1, X2,Y2, and X3,Y3 in COLOR.
This function draws an outline of a triangle whereas ‘fill-triangle’ fills the
triangle with the specified color."
  (format (inkplate-output-port device)
          "#6(~3,'0d,~3,'0d,~3,'0d,~3,'0d,~3,'0d,~3,'0d,~2,'0d)*"
          x1 y1 x2 y2 x3 y3 color))

(define (draw-rounded-rectangle device x y width height radius color)
  "Draw a rounded rectangle on DEVICE at X,Y WIDTH wide by HEIGHT high.
RADIUS is the radius of the rounded corners. Draw the rectangle in COLOR."
  (format (inkplate-output-port device)
          "#7(~3,'0d,~3,'0d,~3,'0d,~3,'0d,~3,'0d,~2,'0d)*"
          x y width height radius color))

(define (fill-rectangle device x y width height color)
  "Draw a rectangle on DEVICE at X,Y WIDTH wide by HEIGHT high in COLOR.
This function fills the entire rectangle with COLOR while ‘draw-rectangle’ only
draws an outline."
  (format (inkplate-output-port device)
          "#8(~3,'0d,~3,'0d,~3,'0d,~3,'0d,~2,'0d)*" x y width height color))

(define (fill-circle device x y radius color)
  "Draw a circle on DEVICE at X,Y with RADIUS.
This function fills the entire circle with COLOR while ‘draw-circle’ only draws
an outline."
  (format (inkplate-output-port device)
          "#9(~3,'0d,~3,'0d,~3,'0d,~2,'0d)*" x y radius color))

(define (fill-triangle device x1 y1 x2 y2 x3 y3 color)
  "Draw a triangle on DEVICE at points X1,Y1, X2,Y2, and X3,Y3 in COLOR.
This function fills the entire triangle with COLOR while ‘draw-triangle’ only
draws an outline."
  (format (inkplate-output-port device)
          "#A(~3,'0d,~3,'0d,~3,'0d,~3,'0d,~3,'0d,~3,'0d,~2,'0d)*"
          x1 y1 x2 y2 x3 y3 color))

(define (fill-rounded-rectangle device x y width height radius color)
  "Draw a rounded rectangle on DEVICE at X,Y WIDTH wide by HEIGHT high.
CORNER-RADIUS is the radius of the rounded corners. Fill the rectangle with
COLOR."
  (format (inkplate-output-port device)
          "#B(~3,'0d,~3,'0d,~3,'0d,~3,'0d,~3,'0d,~2,'0d)*"
          x y width height radius color))

(define (print device text)
  "Print the TEXT onto the screen of DEVICE.
TEXT should be a hex string as produced by ‘convert-string-to-hex’."
  (format (inkplate-output-port device) "#C(~s)*" text))

(define (set-text-size device size)
  "Set the text size for the next print command to SIZE for DEVICE."
  (format (inkplate-output-port device) "#D(~2,'0d)*" size))

(define (set-cursor device x y)
  "Move the cursor on DEVICE to the X and Y coordinates."
  (format (inkplate-output-port device) "#E(~3,'0d,~3,'0d)*" x y))

(define (set-text-wrap device enable)
  "Enable or disable text wrapping on DEVICE depending on the value of ENABLE.
If ENABLE is #t, enable text wrapping. Otherwise disable it."
  (format (inkplate-output-port device) "#F(~a)*" (if enable "T" "F")))

(define (set-rotation device rotation)
  "Set the screen rotation on DEVICE.
ROTATION can be one of:
- 0: 0 degrees rotation
- 1: 90 degrees rotation
- 2: 180 degrees rotation
- 3: 270 degrees rotation"
  (format (inkplate-output-port device) "#G(~3,'0d)*" rotation))

(define (draw-bitmap device x y path)
  "Draw a bitmap on DEVICE at coordinates X,Y.
PATH should be a path on the SD card and should be a hex string
as produced by ‘inkplate--convert-string-to-hex’. This command
puts a response in the output buffer. It should be one of:

- #H(0)*: Image load failed
- #H(1)*: Image loaded successfully
- #H(-1)*: SD Card Init Error"
  (format (inkplate-output-port device) "#H(~3,'0d,~3,'0d,~s)*" x y path))

(define (set-display-mode device mode)
  "Set the display mode for DEVICE to MODE.
Mode can be one of:
- 1: 1-bit mode
- 3: 3-bit mode"
  (format (inkplate-output-port device) "#I(~d)*" mode))

(define (get-display-mode device)
  "Query the DEVICE for which display mode is active.

This puts one of the following responses into the output buffer:
- #J(0): 1-bit mode
- #J(1): 3-bit mode"
  (display "#J(?)*" (inkplate-output-port device)))

(define (clear-screen device)
  "Send the command to clear the screen to DEVICE."
  (display "#K(1)*" (inkplate-output-port device)))

(define (update device)
  "Send the command to update the display to DEVICE."
  (display "#L(1)*" (inkplate-output-port device)))

(define (partial-update device yy1 xx2 yy2)
  "Send the command to update the display to DEVICE.
Tell it to only do a partial update."
  ;; I guess that xx1 is implicitly 0? It's not mentioned in the documentation.
  (format (inkplate-output-port device) "#M(~3,'0d,~3,'0d,~3,'0d)*" yy1 xx2 yy2))

(define (read-temperature device)
  "Query DEVICE for its current temperature.
This will produce a response in the output buffer in the form or #N(22)* which
means its temperature is 22 degrees Celsius."
  (display "#N(?)*" (inkplate-output-port device)))

(define (read-touchpad device touchpad)
  "Query DEVICE for the state of TOUCHPAD.
TOUCHPAD can be 1, 2, or 3. This will produce a response in the
output buffer which can be read with ‘inkplate-read-output’.
Possible responses are:
- #O(1)*: The touch pad is in the high state
- #O(0)*: The touch pad is in the low state"
  (format (inkplate-output-port device) "#O(~d)*" touchpad))

(define (read-battery device)
  "Query DEVICE for the current voltage on the battery.
This produces a response in the output buffer which can be read using
‘read-output’. The response is in the form of #P(3.65)* meaning the measured
voltage on the battery is 3.65VDC."
  (display "#P(?)*" (inkplate-output-port device)))

(define (panel-supply device enable)
  "Turn DEVICE on or off depending on the value of ENABLE.
If ENABLE is #t turn DEVICE on, otherwise turn it off."
  (format (inkplate-output-port device) "#Q(~d)*" (if enable 1 0)))

(define (get-panel-state device)
  "Query DEVICE for the state of the panel.
This command produces a response in the output buffer which can be read using
‘read-output’. The response can be one of:

- #R(1)*: Panel has power
- #R(0)*: Panel has no power"
  (display "#R(?)*" (inkplate-output-port device)))

(define (draw-image device x y path)
  "Draw an image on DEVICE at coordinates X,Y.
PATH should be a path on the SD card and a hex string as produced by
‘convert-string-to-hex’."
  (format (inkplate-output-port device) "#S(~3,'0d,~3,'0d,~s)*" x y path))

(define (draw-thick-line device x1 y1 x2 y2 thickness color)
  "Draw a line on DEVICE from X1,Y1 to X2,Y2 in THICKNESS and COLOR."
  (format (inkplate-output-port device)
          "#T(~3,'0d,~3,'0d,~3,'0d,~3,'0d,~2,'0d,~2,'0d)*"
          x1 y1 x2 y2 thickness color))

(define (draw-ellipse device x y x-radius y-radius color)
  "Draw an ellipse on DEVICE at coordinates X,Y.
X-RADIUS and Y-RADIUS specify the x and y radius of the ellipse. Draw it in
COLOR."
  (format (inkplate-output-port device)
          "#U(~3,'0d,~3,'0d,~3,'0d,~3,'0d,~2,'0d)*" x y x-radius y-radius color))

(define (fill-ellipse device x y x-radius y-radius color)
  "Draw and fill an ellipse on DEVICE at coordinates X,Y.
X-RADIUS and Y-RADIUS specify the x and y radius of the ellipse. Draw it in
COLOR."
  (format (inkplate-output-port device)
          "#V(~3,'0d,~3,'0d,~3,'0d,~3,'0d,~2,'0d)*" x y x-radius y-radius color))

(define (send device)
  "Send the accumulated commands to DEVICE."
  (force-output (inkplate-output-port device)))