package xrandr

import (
	"fmt"

	"slices"

	"maps"

	"edge-infra.dev/pkg/sds/display/displaymanager/applier/xorg/command"
	"edge-infra.dev/pkg/sds/display/displaymanager/applier/xorg/command/runner"
	"edge-infra.dev/pkg/sds/lib/xorg"
)

const xrandrPath = "/usr/bin/xrandr"

const (
	outputFlag  = "--output"
	modeFlag    = "--mode"
	rotateFlag  = "--rotate"
	primaryFlag = "--primary"
	posFlag     = "--pos"
	rightOfFlag = "--right-of"
)

// Command is able to build an Xrandr command to configure displays and run it.
type Command interface {
	command.Command

	SetOutputMode(outputID xorg.OutputID, mode string)
	SetOutputRotation(outputID xorg.OutputID, rotation string)
	SetOutputAsPrimary(outputID xorg.OutputID)
	SetOutputPosition(outputID xorg.OutputID, xPos, yPos int)
	SetOutputRightOf(outputID, relativeTo xorg.OutputID)
}

// NewXrandrCommand returns a new xrandr.Command implementation.
func NewXrandrCommand(cmdRunner runner.Runner) Command {
	return &xrandrCmd{
		cmdRunner:   cmdRunner,
		displayArgs: displayArgs{},
	}
}

// Map of output IDs to the display's xrandr arguments
type displayArgs map[xorg.OutputID][]string

func (o displayArgs) Args() []string {
	args := []string{}

	// iterate over the sorted keys for consistent output
	outputIDs := slices.Collect(maps.Keys(o))
	slices.Sort(outputIDs)
	for _, outputID := range outputIDs {
		args = append(args, outputFlag)
		args = append(args, outputID.String())
		args = append(args, o[outputID]...)
	}

	return args
}

type xrandrCmd struct {
	cmdRunner runner.Runner
	displayArgs
}

func (x *xrandrCmd) Path() string {
	return xrandrPath
}

func (x *xrandrCmd) Run() error {
	if len(x.displayArgs) == 0 {
		return nil
	}
	return x.cmdRunner.Run(xrandrPath, x.displayArgs.Args()...)
}

func (x *xrandrCmd) SetOutputMode(outputID xorg.OutputID, mode string) {
	// e.g. --mode 1920x1080
	x.displayArgs[outputID] = append(x.displayArgs[outputID], modeFlag, mode)
}

func (x *xrandrCmd) SetOutputRotation(outputID xorg.OutputID, rotation string) {
	// e.g. --orientation normal
	x.displayArgs[outputID] = append(x.displayArgs[outputID], rotateFlag, rotation)
}

func (x *xrandrCmd) SetOutputAsPrimary(outputID xorg.OutputID) {
	// e.g. --primary
	x.displayArgs[outputID] = append(x.displayArgs[outputID], primaryFlag)
}

func (x *xrandrCmd) SetOutputPosition(outputID xorg.OutputID, xPos, yPos int) {
	// e.g. --pos 0x0
	x.displayArgs[outputID] = append(x.displayArgs[outputID], posFlag, fmt.Sprintf("%dx%d", xPos, yPos))
}

func (x *xrandrCmd) SetOutputRightOf(outputID, relativeTo xorg.OutputID) {
	// e.g. --right-of DP1
	x.displayArgs[outputID] = append(x.displayArgs[outputID], rightOfFlag, relativeTo.String())
}