package commandkit

import (
	"io"
	"strings"

	configkit "gitea.maximumdirect.net/eric/ConfigKit"
)

// OutcomeKind classifies the result of a command invocation.
type OutcomeKind string

const (
	// OutcomeSuccess indicates that the operation completed successfully.
	OutcomeSuccess OutcomeKind = "success"
	// OutcomeUsage indicates invalid command syntax or declared input.
	OutcomeUsage OutcomeKind = "usage"
	// OutcomeOperational indicates an operational failure.
	OutcomeOperational OutcomeKind = "operational"
	// OutcomeDomain indicates a result classified by application domain logic.
	OutcomeDomain OutcomeKind = "domain"
)

// DeliveryState describes whether CommandKit completed diagnostic delivery.
type DeliveryState string

const (
	// DeliveryNone indicates that no diagnostic delivery was attempted.
	DeliveryNone DeliveryState = "none"
	// DeliveryComplete indicates that diagnostic delivery completed.
	DeliveryComplete DeliveryState = "complete"
	// DeliveryIncomplete indicates that diagnostic delivery did not complete.
	DeliveryIncomplete DeliveryState = "incomplete"
)

// Diagnostic is a deferred message written to an invocation's error stream.
//
// Write is called by CommandKit's diagnostic delivery path. It should return
// any error encountered while writing. A nil Write function has no output.
type Diagnostic struct {
	// Severity classifies the diagnostic using ConfigKit's public severity type.
	Severity configkit.Severity
	// Write writes the diagnostic to the supplied writer.
	Write func(io.Writer) error
}

// Outcome is the classified result of an operation.
//
// Cause records the operation error. DeliveryError records an error encountered
// while presenting diagnostics or reports; it is kept separate from Cause so
// both failures remain inspectable. Outcome does not implement error.
type Outcome struct {
	// Kind classifies the result.
	Kind OutcomeKind
	// Status is the suggested process status for this result.
	Status int
	// Domain names the application-defined classification when Kind is
	// OutcomeDomain.
	Domain string
	// Cause is the error returned by the operation.
	Cause error
	// DeliveryError is an error encountered while writing a report or
	// diagnostics.
	DeliveryError error
	// DiagnosticDelivery records whether diagnostic writing completed. Its zero
	// value is treated as DeliveryNone by invocation coordination.
	DiagnosticDelivery DeliveryState
	// ReportIncomplete is true when a failed write left a report incomplete.
	ReportIncomplete bool
	// Diagnostics are delivered in slice order by invocation coordination.
	Diagnostics []Diagnostic
}

// Success returns a successful outcome with status 0.
func Success() Outcome {
	return Outcome{Kind: OutcomeSuccess, Status: 0, DiagnosticDelivery: DeliveryNone}
}

// Usage returns a usage outcome with status 2 and the supplied cause.
func Usage(cause error) Outcome {
	return Outcome{Kind: OutcomeUsage, Status: 2, Cause: cause, DiagnosticDelivery: DeliveryNone}
}

// Failure returns an operational outcome with status 1 and the supplied cause.
func Failure(cause error) Outcome {
	return Outcome{Kind: OutcomeOperational, Status: 1, Cause: cause, DiagnosticDelivery: DeliveryNone}
}

// Domain returns an application-domain outcome preserving the supplied name,
// status, and cause.
func Domain(name string, status int, cause error) Outcome {
	return Outcome{Kind: OutcomeDomain, Status: status, Domain: name, Cause: cause, DiagnosticDelivery: DeliveryNone}
}

// MessageDiagnostic returns a diagnostic that writes message followed by a
// newline. The writer's error is returned to the caller.
func MessageDiagnostic(severity configkit.Severity, message string) Diagnostic {
	return Diagnostic{
		Severity: severity,
		Write: func(w io.Writer) error {
			_, err := io.WriteString(w, strings.TrimSuffix(message, "\n")+"\n")
			return err
		},
	}
}