package system

import (
	"time"

	"gobot.io/x/gobot"
)

const (
	// IN gpio direction
	IN = "in"
	// OUT gpio direction
	OUT = "out"
	// HIGH gpio level
	HIGH = 1
	// LOW gpio level
	LOW = 0
)

const (
	digitalPinBiasDefault  = 0 // GPIO uses the hardware default
	digitalPinBiasDisable  = 1 // GPIO has pull disabled
	digitalPinBiasPullDown = 2 // GPIO has pull up enabled
	digitalPinBiasPullUp   = 3 // GPIO has pull down enabled

	// open drain and open source allows the connection of output ports with the same mode (OR logic)
	// * for open drain/collector pull up the ports with an external resistor/load
	// * for open source/emitter pull down the ports with an external resistor/load
	digitalPinDrivePushPull   = 0 // the pin will be driven actively high and	low (default)
	digitalPinDriveOpenDrain  = 1 // the pin will be driven active to low only
	digitalPinDriveOpenSource = 2 // the pin will be driven active to high only

	digitalPinEventNone          = 0 // no event will be triggered on any pin change (default)
	digitalPinEventOnFallingEdge = 1 // an event will be triggered on changes from high to low state
	digitalPinEventOnRisingEdge  = 2 // an event will be triggered on changes from low to high state
	digitalPinEventOnBothEdges   = 3 // an event will be triggered on all changes
)

const (
	// DigitalPinEventRisingEdge indicates an inactive to active event.
	DigitalPinEventRisingEdge = "rising edge"
	// DigitalPinEventFallingEdge indicates an active to inactive event.
	DigitalPinEventFallingEdge = "falling edge"
)

type digitalPinConfig struct {
	label            string
	direction        string
	outInitialState  int
	activeLow        bool
	bias             int
	drive            int
	debouncePeriod   time.Duration
	edge             int
	edgeEventHandler func(lineOffset int, timestamp time.Duration, detectedEdge string, seqno uint32, lseqno uint32)
}

func newDigitalPinConfig(label string, options ...func(gobot.DigitalPinOptioner) bool) *digitalPinConfig {
	cfg := &digitalPinConfig{
		label:     label,
		direction: IN,
	}
	for _, option := range options {
		option(cfg)
	}
	return cfg
}

// WithPinLabel use a pin label, which will replace the default label "gobotio#".
func WithPinLabel(label string) func(gobot.DigitalPinOptioner) bool {
	return func(d gobot.DigitalPinOptioner) bool { return d.SetLabel(label) }
}

// WithPinDirectionOutput initializes the pin as output instead of the default "input".
func WithPinDirectionOutput(initial int) func(gobot.DigitalPinOptioner) bool {
	return func(d gobot.DigitalPinOptioner) bool { return d.SetDirectionOutput(initial) }
}

// WithPinDirectionInput initializes the pin as input.
func WithPinDirectionInput() func(gobot.DigitalPinOptioner) bool {
	return func(d gobot.DigitalPinOptioner) bool { return d.SetDirectionInput() }
}

// WithPinActiveLow initializes the pin with inverse reaction (applies on input and output).
func WithPinActiveLow() func(gobot.DigitalPinOptioner) bool {
	return func(d gobot.DigitalPinOptioner) bool { return d.SetActiveLow() }
}

// WithPinPullDown initializes the pin to be pulled down (high impedance to GND, applies on input and output).
// This is working since Kernel 5.5.
func WithPinPullDown() func(gobot.DigitalPinOptioner) bool {
	return func(d gobot.DigitalPinOptioner) bool { return d.SetBias(digitalPinBiasPullDown) }
}

// WithPinPullUp initializes the pin to be pulled up (high impedance to VDD, applies on input and output).
// This is working since Kernel 5.5.
func WithPinPullUp() func(gobot.DigitalPinOptioner) bool {
	return func(d gobot.DigitalPinOptioner) bool { return d.SetBias(digitalPinBiasPullUp) }
}

// WithPinOpenDrain initializes the output pin to be driven with open drain/collector.
func WithPinOpenDrain() func(gobot.DigitalPinOptioner) bool {
	return func(d gobot.DigitalPinOptioner) bool { return d.SetDrive(digitalPinDriveOpenDrain) }
}

// WithPinOpenSource initializes the output pin to be driven with open source/emitter.
func WithPinOpenSource() func(gobot.DigitalPinOptioner) bool {
	return func(d gobot.DigitalPinOptioner) bool { return d.SetDrive(digitalPinDriveOpenSource) }
}

// WithPinDebounce initializes the input pin to be debounced.
func WithPinDebounce(period time.Duration) func(gobot.DigitalPinOptioner) bool {
	return func(d gobot.DigitalPinOptioner) bool { return d.SetDebounce(period) }
}

// WithPinEventOnFallingEdge initializes the input pin for edge detection and call the event handler on falling edges.
func WithPinEventOnFallingEdge(handler func(lineOffset int, timestamp time.Duration, detectedEdge string, seqno uint32,
	lseqno uint32)) func(gobot.DigitalPinOptioner) bool {
	return func(d gobot.DigitalPinOptioner) bool {
		return d.SetEventHandlerForEdge(handler, digitalPinEventOnFallingEdge)
	}
}

// WithPinEventOnRisingEdge initializes the input pin for edge detection and call the event handler on rising edges.
func WithPinEventOnRisingEdge(handler func(lineOffset int, timestamp time.Duration, detectedEdge string, seqno uint32,
	lseqno uint32)) func(gobot.DigitalPinOptioner) bool {
	return func(d gobot.DigitalPinOptioner) bool {
		return d.SetEventHandlerForEdge(handler, digitalPinEventOnRisingEdge)
	}
}

// WithPinEventOnBothEdges initializes the input pin for edge detection and call the event handler on all edges.
func WithPinEventOnBothEdges(handler func(lineOffset int, timestamp time.Duration, detectedEdge string, seqno uint32,
	lseqno uint32)) func(gobot.DigitalPinOptioner) bool {
	return func(d gobot.DigitalPinOptioner) bool {
		return d.SetEventHandlerForEdge(handler, digitalPinEventOnBothEdges)
	}
}

// SetLabel sets the label to use for next reconfigure. The function is intended to use by WithPinLabel().
func (d *digitalPinConfig) SetLabel(label string) bool {
	if d.label == label {
		return false
	}
	d.label = label
	return true
}

// SetDirectionOutput sets the direction to output for next reconfigure. The function is intended to use
// by WithPinDirectionOutput().
func (d *digitalPinConfig) SetDirectionOutput(initial int) bool {
	if d.direction == OUT {
		// in this case also the initial value will not be written
		return false
	}
	d.direction = OUT
	d.outInitialState = initial
	return true
}

// SetDirectionInput sets the direction to input for next reconfigure. The function is intended to use
// by WithPinDirectionInput().
func (d *digitalPinConfig) SetDirectionInput() bool {
	if d.direction == IN {
		return false
	}
	d.direction = IN
	return true
}

// SetActiveLow sets the pin with inverse reaction (applies on input and output) for next reconfigure. The function
// is intended to use by WithPinActiveLow().
func (d *digitalPinConfig) SetActiveLow() bool {
	if d.activeLow {
		return false
	}
	d.activeLow = true
	return true
}

// SetBias sets the pin bias (applies on input and output) for next reconfigure. The function
// is intended to use by WithPinPullUp() and WithPinPullDown().
func (d *digitalPinConfig) SetBias(bias int) bool {
	if d.bias == bias {
		return false
	}
	d.bias = bias
	return true
}

// SetDrive sets the pin drive mode (applies on output only) for next reconfigure. The function
// is intended to use by WithPinOpenDrain(), WithPinOpenSource() and WithPinPushPull().
func (d *digitalPinConfig) SetDrive(drive int) bool {
	if d.drive == drive {
		return false
	}
	d.drive = drive
	return true
}

// SetDebounce sets the input pin with the given debounce period for next reconfigure. The function
// is intended to use by WithPinDebounce().
func (d *digitalPinConfig) SetDebounce(period time.Duration) bool {
	if d.debouncePeriod == period {
		return false
	}
	d.debouncePeriod = period
	return true
}

// SetEventHandlerForEdge sets the input pin to edge detection and to call the event handler on specified edge. The
// function is intended to use by WithPinEventOnFallingEdge(), WithPinEventOnRisingEdge() and WithPinEventOnBothEdges().
func (d *digitalPinConfig) SetEventHandlerForEdge(handler func(int, time.Duration, string, uint32, uint32), edge int) bool {
	if d.edge == edge {
		return false
	}
	d.edge = edge
	d.edgeEventHandler = handler
	return true
}