package exiter

import (
	"errors"

	"gitlab.com/CRThaze/cworthy/exit"
)

// ExitCode represents an unsigned 16 bit integer used to define exit statuses.
type ExitCode exit.ExitT

const (
	ExitOK          ExitCode = ExitCode(exit.EX_OK)          // 0: successful termination
	ExitError       ExitCode = ExitCode(1)                   // 1: generic error
	ExitUsage       ExitCode = ExitCode(exit.EX_USAGE)       // 64: command line usage error
	ExitDataErr     ExitCode = ExitCode(exit.EX_DATAERR)     // 65: data format error
	ExitNoInput     ExitCode = ExitCode(exit.EX_NOINPUT)     // 66: cannot open input
	ExitNoUser      ExitCode = ExitCode(exit.EX_NOUSER)      // 67: addressee unknown
	ExitNoHost      ExitCode = ExitCode(exit.EX_NOHOST)      // 68: host name unknown
	ExitUnavailable ExitCode = ExitCode(exit.EX_UNAVAILABLE) // 69: service unavailable
	ExitSoftware    ExitCode = ExitCode(exit.EX_SOFTWARE)    // 70: internal software error
	ExitOSErr       ExitCode = ExitCode(exit.EX_OSERR)       // 71: system error (e.g., can't fork)
	ExitOSFile      ExitCode = ExitCode(exit.EX_OSFILE)      // 72: critical OS file missing
	ExitCantCreate  ExitCode = ExitCode(exit.EX_CANTCREAT)   // 73: can't create (user) output file
	ExitIOErr       ExitCode = ExitCode(exit.EX_IOERR)       // 74: input/output error
	ExitTempFail    ExitCode = ExitCode(exit.EX_TEMPFAIL)    // 75: temp failure; user is invited to retry
	ExitProtocol    ExitCode = ExitCode(exit.EX_PROTOCOL)    // 76: remote error in protocol
	ExitNoPerm      ExitCode = ExitCode(exit.EX_NOPERM)      // 77: permission denied
	ExitConfig      ExitCode = ExitCode(exit.EX_CONFIG)      // 78: configuration error
	ExitAbort       ExitCode = ExitCode(exit.EX_ABORT)       // 134: process was aborted
)

var exitCodeDescs [^ExitCode(0)]string

func init() {
	exitCodeDescs = exit.GetAllExitCodeDescriptions()
	exitCodeDescs[ExitError] = "generic error"
}

// Desc returns the description string for a given ExitCode.
func (e ExitCode) Desc() string {
	return exitCodeDescs[e]
}

// RegisterNewExitCode reserves an ExitCode and stores its corresponding
// description string for recall.
// It returns an error if the given integer is already in use or outside the
// usable range. And also if the description string is empty.
func RegisterNewExitCode(num int, desc string) (ExitCode, error) {
	if num < 0 || num > int(^ExitCode(0)) {
		return 0, errors.New("New exit code out of range")
	}
	if num == 0 || num == int(exit.EX_ABORT) || (num >= int(exit.EX__BASE) && num <= int(exit.EX__MAX)) {
		return 0, errors.New("New exit code not user reservable")
	}
	if exitCodeDescs[num] != "" {
		return 0, errors.New("New exit code already defined")
	}
	if desc == "" {
		return 0, errors.New("New exit code description cannot be blank")
	}
	exitCodeDescs[num] = desc
	return ExitCode(num), nil
}

// RegisterNextExitCode find the next available ExitCode number and associates the
// given description string with it.
// It returns an error if there are no more available numbers to reserve.
func RegisterNextExitCode(desc string) (ExitCode, error) {
	nextUsable := func(n int) int {
		n++
		for n == int(exit.EX_ABORT) || (n >= int(exit.EX__BASE) && n <= int(exit.EX__MAX)) {
			n++
		}
		return n
	}
	for i := 1; i <= int(^ExitCode(0)); i = nextUsable(i) {
		if exitCodeDescs[i] == "" {
			exitCodeDescs[i] = desc
			return ExitCode(i), nil
		}
	}
	return 0, errors.New("Available exit codes exhausted")
}

func mapCodes(codes []string, offset int, m map[ExitCode]string) {
	for i, desc := range codes {
		if desc != "" {
			m[ExitCode(i+offset)] = desc
		}
	}
}

// UserCodeMap returns a map of ExitCodes and their associated description strings
// with in the User-Definable range.
func UserCodeMap() (m map[ExitCode]string) {
	m = map[ExitCode]string{}
	mapCodes(exitCodeDescs[1:exit.EX__BASE], 1, m)
	mapCodes(exitCodeDescs[exit.EX__MAX+1:exit.EX_ABORT], int(exit.EX__MAX)+1, m)
	mapCodes(exitCodeDescs[exit.EX_ABORT+1:], int(exit.EX_ABORT)+1, m)
	return
}

// FullCodeMap returns a map of all ExitCodes and their associated description
// strings.
func FullCodeMap() (m map[ExitCode]string) {
	m = map[ExitCode]string{}
	mapCodes(exitCodeDescs[:], 0, m)
	return
}

// GetAllExitCodeDescriptions returns an array of all possible ExitCode description
// strings (where the index is the exit code). Any unreserved ExitCodes are also
// included with empty string descriptions.
func GetAllExitCodeDescriptions() [^ExitCode(0)]string {
	return exitCodeDescs
}