package knowledge

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

var contentKeyPattern = regexp.MustCompile(`^[A-Za-z][A-Za-z0-9_]{0,63}$`)
var placeholderPattern = regexp.MustCompile(`\{\{\s*((?:input|card)\.[A-Za-z][A-Za-z0-9_]*)\s*\}\}`)

type CardField struct {
	Key         string      `json:"key"`
	Name        string      `json:"name"`
	Value       interface{} `json:"value"`
	SourceField string      `json:"source_field,omitempty"`
}

type CopyTemplate struct {
	ID      string `json:"id"`
	Title   string `json:"title"`
	Content string `json:"content"`
}

type Content struct {
	Fields        []CardField    `json:"fields,omitempty"`
	CopyTemplates []CopyTemplate `json:"copy_templates,omitempty"`
	StandardCopy  string         `json:"standard_copy,omitempty"`
	ForbiddenCopy string         `json:"forbidden_copy,omitempty"`
	RiskNote      string         `json:"risk_note,omitempty"`
}

type RenderedCopy struct {
	ID      string `json:"id"`
	Title   string `json:"title"`
	Content string `json:"content"`
}

func ParseContent(raw []byte) (Content, error) {
	var content Content
	if err := json.Unmarshal(raw, &content); err != nil {
		return Content{}, errors.New("知识卡内容必须是 JSON 对象")
	}
	return normalizeAndValidate(content)
}

func ParseContentMap(value map[string]interface{}) (Content, error) {
	raw, err := json.Marshal(value)
	if err != nil {
		return Content{}, err
	}
	return ParseContent(raw)
}

func ValidateReferences(content Content, scenarioFieldKeys map[string]bool) error {
	cardFieldKeys := make(map[string]bool, len(content.Fields))
	for _, field := range content.Fields {
		cardFieldKeys[field.Key] = true
		if field.SourceField != "" && !scenarioFieldKeys[field.SourceField] {
			return fmt.Errorf("知识字段“%s”关联的场景字段“%s”不存在", field.Name, field.SourceField)
		}
	}
	for _, template := range content.CopyTemplates {
		for _, match := range placeholderPattern.FindAllStringSubmatch(template.Content, -1) {
			if len(match) != 2 {
				continue
			}
			parts := strings.SplitN(match[1], ".", 2)
			if len(parts) != 2 {
				continue
			}
			switch parts[0] {
			case "input":
				if !scenarioFieldKeys[parts[1]] {
					return fmt.Errorf("话术“%s”引用的场景字段“%s”不存在", template.Title, parts[1])
				}
			case "card":
				if !cardFieldKeys[parts[1]] {
					return fmt.Errorf("话术“%s”引用的知识字段“%s”不存在", template.Title, parts[1])
				}
			}
		}
	}
	return nil
}

func Render(content Content, answers map[string]interface{}) []RenderedCopy {
	values := make(map[string]string, len(answers)+len(content.Fields)*2)
	for key, value := range answers {
		values["input."+key] = displayValue(value)
	}
	for _, field := range content.Fields {
		value := field.Value
		if field.SourceField != "" {
			if answer, ok := answers[field.SourceField]; ok && hasValue(answer) {
				value = answer
			}
		}
		values["card."+field.Key] = displayValue(value)
	}
	copies := make([]RenderedCopy, 0, len(content.CopyTemplates))
	for _, template := range content.CopyTemplates {
		copies = append(copies, RenderedCopy{ID: template.ID, Title: template.Title, Content: placeholderPattern.ReplaceAllStringFunc(template.Content, func(token string) string {
			matches := placeholderPattern.FindStringSubmatch(token)
			if len(matches) != 2 || values[matches[1]] == "" {
				return "未提供"
			}
			return values[matches[1]]
		})})
	}
	return copies
}

func PrimaryCopy(content Content) string {
	if len(content.CopyTemplates) > 0 {
		return content.CopyTemplates[0].Content
	}
	return content.StandardCopy
}

func normalizeAndValidate(content Content) (Content, error) {
	content.StandardCopy = strings.TrimSpace(content.StandardCopy)
	content.ForbiddenCopy = strings.TrimSpace(content.ForbiddenCopy)
	content.RiskNote = strings.TrimSpace(content.RiskNote)
	if len(content.CopyTemplates) == 0 && content.StandardCopy != "" {
		content.CopyTemplates = []CopyTemplate{{ID: "default", Title: "标准话术", Content: content.StandardCopy}}
	}
	if len(content.CopyTemplates) == 0 {
		return Content{}, errors.New("请至少填写一条话术模板")
	}
	seenFields := map[string]bool{}
	for i := range content.Fields {
		field := &content.Fields[i]
		field.Key = strings.TrimSpace(field.Key)
		field.Name = strings.TrimSpace(field.Name)
		field.SourceField = strings.TrimSpace(field.SourceField)
		if !contentKeyPattern.MatchString(field.Key) || field.Name == "" {
			return Content{}, errors.New("知识字段需要有效的字段标识和字段名称")
		}
		if seenFields[field.Key] {
			return Content{}, fmt.Errorf("知识字段标识“%s”重复", field.Key)
		}
		if field.SourceField != "" && !contentKeyPattern.MatchString(field.SourceField) {
			return Content{}, fmt.Errorf("知识字段“%s”的关联字段标识不正确", field.Name)
		}
		seenFields[field.Key] = true
	}
	seenTemplates := map[string]bool{}
	for i := range content.CopyTemplates {
		template := &content.CopyTemplates[i]
		template.ID = strings.TrimSpace(template.ID)
		template.Title = strings.TrimSpace(template.Title)
		template.Content = strings.TrimSpace(template.Content)
		if !contentKeyPattern.MatchString(template.ID) || template.Title == "" || template.Content == "" {
			return Content{}, errors.New("每条话术需要有效的标识、标题和内容")
		}
		if seenTemplates[template.ID] {
			return Content{}, fmt.Errorf("话术标识“%s”重复", template.ID)
		}
		seenTemplates[template.ID] = true
	}
	if content.StandardCopy == "" {
		content.StandardCopy = content.CopyTemplates[0].Content
	}
	return content, nil
}

func hasValue(value interface{}) bool {
	if value == nil {
		return false
	}
	return strings.TrimSpace(displayValue(value)) != ""
}

func displayValue(value interface{}) string {
	switch typed := value.(type) {
	case nil:
		return ""
	case bool:
		if typed {
			return "是"
		}
		return "否"
	case []interface{}:
		items := make([]string, 0, len(typed))
		for _, item := range typed {
			items = append(items, displayValue(item))
		}
		return strings.Join(items, "、")
	case []string:
		return strings.Join(typed, "、")
	default:
		return fmt.Sprint(value)
	}
}