package engine

import (
	"errors"
	"fmt"

	"jarl/internal/bind"
	"jarl/internal/validate"
)

// ErrorKind classifies engine errors (the API maps them to HTTP status
// codes).
type ErrorKind string

const (
	KindBadRequest ErrorKind = "bad_request"       // malformed or invalid input
	KindForbidden  ErrorKind = "forbidden"         // permission denied
	KindNotFound   ErrorKind = "not_found"         // object does not exist
	KindConflict   ErrorKind = "conflict"          // concurrent change, wrong state
	KindValidation ErrorKind = "validation_failed" // the resulting config has errors
	KindBIND       ErrorKind = "bind_failed"       // named-checkconf or rndc failed
	KindDrift      ErrorKind = "drift"             // files were changed outside Jarl
	KindNotAdopted ErrorKind = "not_adopted"       // named does not load Jarl's config yet
)

// Error is an engine error with details for the caller.
type Error struct {
	Kind    ErrorKind `json:"code"`
	Message string    `json:"message"`
	OpSeq   int       `json:"op,omitempty"` // the operation that failed
	// OpSummary describes that operation, so people can find it in the
	// changeset (record IDs mean little to them).
	OpSummary string             `json:"op_summary,omitempty"`
	Problems  []validate.Problem `json:"problems,omitempty"`
	Check     []CheckMessage     `json:"check,omitempty"`
	Diff      string             `json:"diff,omitempty"`
}

func (e *Error) Error() string {
	if e.OpSeq > 0 && e.OpSummary != "" {
		return fmt.Sprintf("operation %d (%s): %s", e.OpSeq, e.OpSummary, e.Message)
	}
	if e.OpSeq > 0 {
		return fmt.Sprintf("operation %d: %s", e.OpSeq, e.Message)
	}
	return e.Message
}

func errf(kind ErrorKind, format string, args ...any) *Error {
	return &Error{Kind: kind, Message: fmt.Sprintf(format, args...)}
}

// AsError returns err as *Error, if it is one.
func AsError(err error) (*Error, bool) {
	var e *Error
	ok := errors.As(err, &e)
	return e, ok
}

// CheckMessage is a named-checkconf message mapped back to the Jarl object
// that produced the offending line.
type CheckMessage struct {
	bind.Message
	ObjectType string `json:"object_type,omitempty"`
	ObjectID   int64  `json:"object_id,omitempty"`
	Object     string `json:"object,omitempty"`
}