package zerr

import (
	"context"
	"fmt"
	"log/slog"
	"strconv"
	"strings"
	"time"

	"connectrpc.com/connect"
	"gitlab.bareksa.com/backend/zen/core/zoptions"
)

type Err struct {
	message       string
	publicMessage string
	code          connect.Code
	errs          []error
	caller        uintptr
	details       []any
	time          time.Time
	id            string
	logger        Logger
	notifier      Notifier
	sequence      *Sequence
}

func (mu *Err) Error() string {
	if len(mu.errs) == 0 {
		return "[nil]"
	}
	s := strings.Builder{}
	if len(mu.errs) == 1 {
		str := getNestedErrorString(mu.errs[0])
		str, found := strings.CutPrefix(str, mu.message)
		if found {
			str, _ = strings.CutPrefix(str, ": ")
		}
		s.WriteString(mu.message)
		s.WriteString(": ")
		s.WriteString(str)
		return s.String()
	}
	s.WriteString(mu.message)
	for i, e := range mu.errs {
		if i > 0 {
			s.WriteString("\n")
		}
		s.WriteString(strconv.Itoa(i + 1))
		s.WriteString(". ")
		s.WriteString(getNestedErrorString(e))
	}
	return s.String()
}

func getNestedErrorString(err error) string {
	if err == nil {
		return "[nil]"
	}
	s := strings.Builder{}
	if e, ok := err.(interface{ Unwrap() error }); ok {
		current := err.Error()
		if err := e.Unwrap(); err != nil {
			next := getNestedErrorString(err)
			hasPrefix := strings.HasPrefix(next, current)
			if !hasPrefix {
				s.WriteString(current)
				s.WriteString(": ")
			}
			s.WriteString(next)
		}
	}

	if errs, ok := err.(interface{ Unwrap() []error }); ok {
		for i, e := range errs.Unwrap() {
			if i > 0 {
				s.WriteString("\n")
			}
			s.WriteString(strconv.Itoa(i + 1))
			s.WriteString(". ")
			s.WriteString(getNestedErrorString(e))
		}
	}

	if s.Len() == 0 {
		s.WriteString(err.Error())
	}

	return s.String()
}

// LogValue returns log fields to be consumed by logger.
func (mu *Err) LogValue() slog.Value {
	attrs := make([]slog.Attr, 0, len(mu.errs))
	i := 0
	for _, err := range mu.errs {
		if err == nil {
			continue
		}
		i++
		attrs = append(attrs, slog.Attr{
			Key:   strconv.Itoa(i),
			Value: errorValuer{err}.LogValue(),
		})
	}
	return slog.GroupValue(attrs...)
}

// Code sets error code. Ignored in Multi.
func (mu *Err) Code(code connect.Code) Error {
	mu.code = code
	return mu
}

// GetCode Always returns 0 in Multi.
func (mu *Err) GetCode() connect.Code {
	return mu.code
}

// Message sets error message. It uses fmt.Sprintf to format the message.
func (mu *Err) Message(msg string, args ...any) Error {
	mu.message = fmt.Sprintf(msg, args...)
	return mu
}

func (mu *Err) GetMessage() string {
	return mu.message
}

func (mu *Err) PublicMessage(msg string, args ...any) Error {
	mu.publicMessage = fmt.Sprintf(msg, args...)
	return mu
}

func (mu *Err) GetPublicMessage() string {
	return mu.publicMessage
}

func (mu *Err) Caller(pc uintptr) Error {
	mu.caller = pc
	return mu
}

func (mu *Err) GetCaller() uintptr {
	return mu.caller
}

// Details sets error details. It's a key-value pair where the odd index is the key and the even index is the value.
//
// Invalid key-value pair number and format will cause the misplaced value to be paired up with "!BADKEY".
//
// Example:
//
//	err.Details(
//	  "key1", 12345,
//	  "key2", float64(12345.67),
//	)
func (mu *Err) Details(fields ...any) Error {
	mu.details = fields
	return mu
}

func (mu *Err) GetDetails() []any {
	return mu.details
}

// Time sets the error time.
//
// Time is already set to current when the error is created or wrapped,
// so this method is only useful when you want to set a different time.
func (mu *Err) Time(t time.Time) Error {
	mu.time = t
	return mu
}

func (mu *Err) GetTime() time.Time {
	return mu.time
}

// ID sets the error ID.
//
// ID is used to identify the error. Used by Zen to consider if an error is the same as another.
//
// Current implementation
func (mu *Err) ID(msg string, args ...any) Error {
	mu.id = fmt.Sprintf(msg, args...)
	return mu
}

func (mu *Err) GetID() string {
	return mu.id
}

func (mu *Err) Log(ctx context.Context) Error {
	mu.logger.Log(ctx, mu)
	return mu
}

func (mu *Err) Notify(ctx context.Context, opts ...zoptions.NotifyOption) Error {
	mu.notifier.Notify(ctx, mu, opts...)
	return mu
}

// Sequence returns the state of the error sequence.
func (mu *Err) Sequence() *Sequence {
	return mu.sequence
}

func (mu *Err) Unwrap() []error {
	return mu.errs
}