package main

import (
	"flag"
	"fmt"
	"math"
	"os"

	"go.einride.tech/can/pkg/dbc"

	"git.samanthony.xyz/can_gauge_interface/sw/cal/canbus"
)

type Signals struct {
	tach, speed, an1, an2, an3, an4 *dbc.SignalDef
}

// Flags
var (
	// DBC file
	dbcFilenameFlag = "dbc"
	dbcFilename     = flag.String(dbcFilenameFlag, "", "DBC file")

	// SocketCAN device
	canDev = flag.String("can", "can0", "SocketCAN device")

	// Signal names
	tachSig  = flag.String("tachsig", "", "tachometer signal name")
	speedSig = flag.String("speedsig", "", "speedometer signal name")
	an1Sig   = flag.String("an1sig", "", "analog channel 1 signal name")
	an2Sig   = flag.String("an2sig", "", "analog channel 2 signal name")
	an3Sig   = flag.String("an3sig", "", "analog channel 3 signal name")
	an4Sig   = flag.String("an4sig", "", "analog channel 4 signal name")

	// Calibration tables
	tachTblFlag  = "tachtbl"
	speedTblFlag = "speedtbl"
	an1TblFlag   = "an1tbl"
	an2TblFlag   = "an2tbl"
	an3TblFlag   = "an3tbl"
	an4TblFlag   = "an4tbl"
	tachTbl      = flag.String(tachTblFlag, "", "tachometer calibration CSV file")
	speedTbl     = flag.String(speedTblFlag, "", "speedometer calibration CSV file")
	an1Tbl       = flag.String(an1TblFlag, "", "analog channel 1 calibration CSV file")
	an2Tbl       = flag.String(an2TblFlag, "", "analog channel 2 calibration CSV file")
	an3Tbl       = flag.String(an3TblFlag, "", "analog channel 3 calibration CSV file")
	an4Tbl       = flag.String(an4TblFlag, "", "analog channel 4 calibration CSV file")
)

func main() {
	// Parse command line args
	flag.Parse()
	if *dbcFilename == "" {
		weprintf("Missing flag: -%s\n", dbcFilenameFlag)
		flag.Usage()
		os.Exit(1)
	}
	if err := checkTablesProvided(); err != nil {
		eprintf("%v\n", err)
	}
	sigNames := nonEmpty(*tachSig, *speedSig, *an1Sig, *an2Sig, *an3Sig, *an4Sig)
	tblFilenames := nonEmpty(*tachTbl, *speedTbl, *an1Tbl, *an2Tbl, *an3Tbl, *an4Tbl)

	// Open CAN connection
	fmt.Println("Opening connection to", *canDev)
	bus, err := canbus.Connect(*canDev)
	if err != nil {
		eprintf("%v\n", err)
	}
	defer bus.Close()

	// Parse DBC file and transmit encoding of each signal
	if err := sendEncodings(*dbcFilename, sigNames, bus); err != nil {
		eprintf("%v\n", err)
	}

	// Parse tables and transmit them
	if err := sendTables(tblFilenames, bus); err != nil {
		eprintf("%v\n", err)
	}
}

// Return a map of non-empty strings keyed by their index in the given list.
func nonEmpty(ss ...string) map[uint8]string {
	if len(ss) > math.MaxUint8 {
		panic(len(ss))
	}

	m := make(map[uint8]string)
	for i := range ss {
		if ss[i] != "" {
			m[uint8(i)] = ss[i]
		}
	}
	return m
}

// Check that the user provided a corresponding table for each signal they gave.
func checkTablesProvided() error {
	signals := []string{*tachSig, *speedSig, *an1Sig, *an2Sig, *an3Sig, *an4Sig}
	tables := []string{*tachTbl, *speedTbl, *an1Tbl, *an2Tbl, *an3Tbl, *an4Tbl}
	tableFlags := []string{tachTblFlag, speedTblFlag, an1TblFlag, an2TblFlag, an3TblFlag, an4TblFlag}
	for i := range signals {
		if signals[i] != "" && tables[i] == "" {
			// No corresponding table
			return fmt.Errorf("Missing flag -%s", tableFlags[i])
		}
	}
	return nil // all present signals have a matching table
}

// Parse DBC file and transmit encoding of each signal using Signal Control frames.
func sendEncodings(dbcFilename string, sigNames map[uint8]string, bus canbus.Bus) error {
	// Parse DBC file
	fmt.Println("Parsing", dbcFilename)
	sigs, err := parseSignals(dbcFilename, sigNames)
	if err != nil {
		return err
	}

	// Transmit Signal Control frames
	for _, sig := range sigs {
		fmt.Println("Sending signal encoding", sig)
		if err := sig.SendEncoding(bus); err != nil {
			return err
		}
		fmt.Printf("Signal encoding %d OK\n", sig.index)
	}

	return nil
}

// Parse each table and transmit them using Table Control frames.
func sendTables(tblFilenames map[uint8]string, bus canbus.Bus) error {
	for k, filename := range tblFilenames {
		fmt.Printf("Parsing table %d: %s\n", k, filename)
		tbl, err := parseTable(filename, k)
		if err != nil {
			return err
		}

		fmt.Printf("Sending table %d\n", k)
		if err := tbl.Send(bus); err != nil {
			return err
		}
		fmt.Printf("Table %d OK\n", k)
	}
	return nil
}