package prompt

import (
	"context"
	"encoding/json"
	"fmt"
	"prompts-core/common/util"
	"strings"

	"prompts-core/dao"
	"prompts-core/model/entity"
)

// PromptIR 统一 Prompt 中间表示
type PromptIR struct {
	System  []Segment `json:"system"`
	History []Segment `json:"history"`
	User    []Segment `json:"user"`
}

// Segment 消息片段
type Segment struct {
	Type    string `json:"type"`
	Content string `json:"content"`
	Role    string `json:"role,omitempty"`
}

// ProviderProtocol 协议编译配置（从 DB JSONB 字段解析）
type ProviderProtocol struct {
	TargetField          string            `json:"target_field"`
	MergeOrder           []string          `json:"merge_order"`
	RoleMapping          map[string]string `json:"role_mapping"`
	ContentMapping       ContentMapping    `json:"content_mapping"`
	RequestTemplate      map[string]any    `json:"request_template"`
	SystemPromptTemplate string            `json:"system_prompt_template"`
}

// ContentMapping 内容字段映射
type ContentMapping struct {
	Type  string `json:"type"`
	Field string `json:"field"`
}

// NewPromptIR 创建空 PromptIR
func NewPromptIR() *PromptIR {
	return &PromptIR{
		System:  make([]Segment, 0),
		History: make([]Segment, 0),
		User:    make([]Segment, 0),
	}
}

// String 返回 PromptIR 的完整内容字符串（用于 token 计算）
func (ir *PromptIR) String() string {
	var builder strings.Builder

	for _, seg := range ir.System {
		builder.WriteString("System: ")
		builder.WriteString(seg.Content)
		builder.WriteString("\n")
	}

	for _, seg := range ir.History {
		builder.WriteString(seg.Role)
		builder.WriteString(": ")
		builder.WriteString(seg.Content)
		builder.WriteString("\n")
	}

	for _, seg := range ir.User {
		builder.WriteString("User: ")
		builder.WriteString(seg.Content)
		builder.WriteString("\n")
	}

	return builder.String()
}

// GetTotalContent 获取所有内容的拼接字符串（更精确的 token 计算）
func (ir *PromptIR) GetTotalContent() string {
	var builder strings.Builder

	for _, seg := range ir.System {
		builder.WriteString(seg.Content)
		builder.WriteString("\n")
	}

	for _, seg := range ir.History {
		builder.WriteString(seg.Content)
		builder.WriteString("\n")
	}

	for _, seg := range ir.User {
		builder.WriteString(seg.Content)
		builder.WriteString("\n")
	}

	return builder.String()
}

// AddSystem 添加系统提示
func (ir *PromptIR) AddSystem(content string) *PromptIR {
	if content != "" {
		ir.System = append(ir.System, Segment{Type: "text", Content: content})
	}
	return ir
}

// AddUser 添加用户消息
func (ir *PromptIR) AddUser(content string) *PromptIR {
	if content != "" {
		ir.User = append(ir.User, Segment{Type: "text", Content: content})
	}
	return ir
}

// AddHistory 添加历史消息
func (ir *PromptIR) AddHistory(role, content string) *PromptIR {
	if content != "" {
		ir.History = append(ir.History, Segment{Type: "text", Content: content, Role: role})
	}
	return ir
}

// ToMessages 转换为 OpenAI 兼容的 messages 格式（MVP 默认）
func (ir *PromptIR) ToMessages() []map[string]any {
	var messages []map[string]any

	for _, seg := range ir.System {
		messages = append(messages, map[string]any{
			"role":    "system",
			"content": seg.Content,
		})
	}

	for _, seg := range ir.History {
		messages = append(messages, map[string]any{
			"role":    seg.Role,
			"content": seg.Content,
		})
	}

	for _, seg := range ir.User {
		messages = append(messages, map[string]any{
			"role":    "user",
			"content": seg.Content,
		})
	}

	return messages
}

// GetProtocolByProvider 根据 provider_name 获取协议配置
func GetProtocolByProvider(ctx context.Context, providerName string) (*ProviderProtocol, error) {
	entity, err := dao.ProviderProtocol.Get(ctx, &entity.ProviderProtocol{
		ProviderName: providerName,
		Status:       1,
	})
	if err != nil || entity == nil {
		return nil, err
	}
	return parseProtocol(entity), nil
}

// parseProtocol 将 DB entity 转为编译用协议配置
func parseProtocol(e *entity.ProviderProtocol) *ProviderProtocol {
	p := &ProviderProtocol{
		TargetField:          e.TargetField,
		SystemPromptTemplate: e.SystemPromptTemplate,
	}

	// 使用通用解析方法处理各个字段
	util.ParseJSONFieldFromGvar(e.MergeOrder, &p.MergeOrder)
	util.ParseJSONFieldFromGvar(e.RoleMapping, &p.RoleMapping)
	util.ParseJSONFieldFromGvar(e.ContentMapping, &p.ContentMapping)
	util.ParseJSONFieldFromGvar(e.RequestTemplate, &p.RequestTemplate)
	return p
}

// Compile 将 PromptIR 按协议配置编译为 Provider Request
func Compile(ir *PromptIR, p *ProviderProtocol, chatModel *entity.AsynchModel) (map[string]any, error) {
	if ir == nil || p == nil {
		return nil, fmt.Errorf("ir and protocol are required")
	}
	messages := mergeByOrder(ir, p.MergeOrder)
	messages = mapRoles(messages, p.RoleMapping)
	messages = mapContent(messages, p.ContentMapping)

	return buildRequest(messages, p, chatModel), nil
}

// mergeByOrder 按协议配置顺序拼接消息
func mergeByOrder(ir *PromptIR, order []string) []map[string]any {
	var messages []map[string]any

	for _, part := range order {
		switch part {
		case "system":
			for _, seg := range ir.System {
				messages = append(messages, map[string]any{
					"role":    "system",
					"content": seg.Content,
				})
			}
		case "history":
			for _, seg := range ir.History {
				messages = append(messages, map[string]any{
					"role":    seg.Role,
					"content": seg.Content,
				})
			}
		case "user":
			for _, seg := range ir.User {
				messages = append(messages, map[string]any{
					"role":    "user",
					"content": seg.Content,
				})
			}
		}
	}

	return messages
}

// mapRoles 角色映射
func mapRoles(messages []map[string]any, mapping map[string]string) []map[string]any {
	if len(mapping) == 0 {
		return messages
	}

	for i, msg := range messages {
		role, ok := msg["role"].(string)
		if !ok {
			continue
		}

		if mapped, exists := mapping[role]; exists {
			messages[i]["role"] = mapped
		}
	}

	return messages
}

// mapContent 内容字段映射
func mapContent(messages []map[string]any, cm ContentMapping) []map[string]any {
	for _, msg := range messages {
		content := msg["content"]
		delete(msg, "content")

		switch cm.Type {
		case "parts":
			msg["parts"] = []map[string]any{
				{cm.Field: content},
			}
		default:
			msg[cm.Field] = content
		}
	}

	return messages
}

// buildRequest 按 target_field 和 request_template 构建请求体
func buildRequest(messages []map[string]any, p *ProviderProtocol, chatModel *entity.AsynchModel) map[string]any {
	if len(p.RequestTemplate) > 0 {
		return renderTemplate(p.RequestTemplate, messages, chatModel)
	}

	return map[string]any{
		p.TargetField: messages,
	}
}

// renderTemplate 简单的 {{key}} 模板替换
func renderTemplate(tmpl map[string]any, messages []map[string]any, chatModel *entity.AsynchModel) map[string]any {
	b, _ := json.Marshal(tmpl)
	str := string(b)

	if chatModel != nil {
		str = strings.ReplaceAll(str, `"{{model}}"`, `"`+chatModel.ModelName+`"`)
	}

	msgBytes, _ := json.Marshal(messages)
	str = strings.ReplaceAll(str, `"{{messages}}"`, string(msgBytes))

	var result map[string]any
	json.Unmarshal([]byte(str), &result)

	return result
}