package mailx

import (
	"encoding/json"
	"fmt"
	"strings"
)

// FromBytes 从 JSON 字节构建消息（便捷入口，用于接入配置/存储）。
func FromBytes(data []byte) (*Message, error) {
	var m Message
	if err := json.Unmarshal(data, &m); err != nil {
		return nil, fmt.Errorf("mailx: unmarshal message: %w", err)
	}
	return &m, nil
}

// FromMap 从 map 构建消息，常用字段自动映射：
//   - from / to / cc / bcc / subject / text / html / body / replyto / reply_to
//   - to/cc/bcc 可为 []string、[]any 或 "a@x.com,b@y.com" 分隔串
//   - attachments: []map{name,path,data} 或 []string(path)
func FromMap(m map[string]any) (*Message, error) {
	if m == nil {
		return nil, fmt.Errorf("%w: map is nil", ErrInvalidConfig)
	}
	msg := &Message{}
	var err error

	str := func(keys ...string) string {
		for _, k := range keys {
			if v, ok := m[k].(string); ok {
				return v
			}
		}
		return ""
	}
	msg.From = str("from")
	msg.Subject = str("subject")
	msg.TextBody = firstNonEmptyStr(str("text"), str("textbody"), str("text_body"))
	msg.Body = firstNonEmptyStr(str("html"), str("body"))
	msg.ReplyTo = firstNonEmptyStr(str("replyto"), str("reply_to"))

	if msg.To, err = toList(m["to"]); err != nil {
		return nil, err
	}
	if msg.Cc, err = toList(m["cc"]); err != nil {
		return nil, err
	}
	if msg.Bcc, err = toList(m["bcc"]); err != nil {
		return nil, err
	}
	if atts, ok := m["attachments"]; ok {
		msg.Attachments, err = toAttachments(atts)
		if err != nil {
			return nil, err
		}
	}
	return msg, nil
}

// toList 将任意输入转为地址列表（[]string、[]any 或逗号/分号分隔串）
func toList(v any) ([]string, error) {
	switch t := v.(type) {
	case nil:
		return nil, nil
	case []string:
		return t, nil
	case string:
		var out []string
		for _, p := range strings.FieldsFunc(t, func(r rune) bool { return r == ',' || r == ';' }) {
			if p = strings.TrimSpace(p); p != "" {
				out = append(out, p)
			}
		}
		return out, nil
	case []any:
		out := make([]string, 0, len(t))
		for _, item := range t {
			if s, ok := item.(string); ok {
				out = append(out, s)
			}
		}
		return out, nil
	default:
		return nil, fmt.Errorf("mailx: invalid address list type %T", v)
	}
}

// toAttachments 将 attachments 输入转为附件列表
func toAttachments(v any) ([]Attachment, error) {
	switch t := v.(type) {
	case []string:
		out := make([]Attachment, 0, len(t))
		for _, p := range t {
			out = append(out, Attachment{Name: fileBaseName(p), Path: p})
		}
		return out, nil
	case []map[string]any:
		out := make([]Attachment, 0, len(t))
		for _, mm := range t {
			var att Attachment
			if name, ok := mm["name"].(string); ok {
				att.Name = name
			}
			if p, ok := mm["path"].(string); ok {
				att.Path = p
				if att.Name == "" {
					att.Name = fileBaseName(p)
				}
			}
			if d, ok := mm["data"]; ok {
				if bs, ok := d.([]byte); ok {
					att.Data = bs
				}
			}
			out = append(out, att)
		}
		return out, nil
	case []any:
		return toAttachments(mapsFromAny(t))
	default:
		return nil, fmt.Errorf("mailx: invalid attachments type %T", v)
	}
}

// mapsFromAny 将 []any 转为 []map[string]any（忽略非 map 元素）
func mapsFromAny(arr []any) []map[string]any {
	out := make([]map[string]any, 0, len(arr))
	for _, item := range arr {
		if mm, ok := item.(map[string]any); ok {
			out = append(out, mm)
		}
	}
	return out
}

func firstNonEmptyStr(vals ...string) string {
	for _, v := range vals {
		if v != "" {
			return v
		}
	}
	return ""
}