// Package prompt implements the deterministic prompt-assembly contract used by
// browser and public generation requests.
package prompt

import (
	"fmt"
	"regexp"
	"sort"
	"strings"
)

type Scene struct {
	ID            string `json:"id"`
	Title         string `json:"title"`
	Visual        string `json:"visual"`
	Camera        string `json:"camera,omitempty"`
	HostLine      string `json:"hostLine,omitempty"`
	Caption       string `json:"caption,omitempty"`
	MaterialLabel string `json:"materialLabel,omitempty"`
}
type Material struct {
	ID    string `json:"id,omitempty"`
	URL   string `json:"url"`
	Type  string `json:"type"`
	Role  string `json:"role,omitempty"`
	Label string `json:"label,omitempty"`
	Name  string `json:"name,omitempty"`
}
type Input struct {
	Mode         string     `json:"mode"`
	ProjectName  string     `json:"projectName,omitempty"`
	Audience     string     `json:"audience,omitempty"`
	Offer        string     `json:"offer,omitempty"`
	BrandLine    string     `json:"brandLine,omitempty"`
	ManualPrompt string     `json:"manualPrompt,omitempty"`
	Storyboard   []Scene    `json:"storyboard,omitempty"`
	Materials    []Material `json:"materials,omitempty"`
	ImageGoal    string     `json:"imageGoal,omitempty"`
	AspectRatio  string     `json:"aspectRatio,omitempty"`
}
type Requirements struct {
	Image int `json:"image"`
	Video int `json:"video"`
	Audio int `json:"audio"`
}
type Result struct {
	Prompt       string       `json:"prompt"`
	Scenes       []Scene      `json:"scenes"`
	Materials    []Material   `json:"materials"`
	Warnings     []string     `json:"warnings"`
	Blocked      bool         `json:"blocked"`
	Requirements Requirements `json:"requirements"`
}

var DefaultScenes = []Scene{
	{ID: "scene-1", Title: "开场画面", Visual: "用上传素材建立项目的第一印象，主体清晰，氛围干净", Camera: "中景或推进镜头", Caption: "项目亮相"},
	{ID: "scene-2", Title: "场景氛围", Visual: "展示空间、环境或使用场景，让观众理解项目所处的真实语境", Camera: "横移或环绕", Caption: "场景氛围"},
	{ID: "scene-3", Title: "核心内容", Visual: "突出核心产品、服务、活动、空间或人物，呈现最重要的信息", Camera: "主体特写", Caption: "核心内容"},
	{ID: "scene-4", Title: "细节补充", Visual: "补充质感、服务、流程、环境或亮点细节，增强可信度", Camera: "细节切镜", Caption: "细节补充"},
	{ID: "scene-5", Title: "收尾画面", Visual: "用项目名称、品牌信息或完整画面收束，形成清楚的结束印象", Camera: "定格或拉远", Caption: "项目记忆点"},
}

func Assemble(input Input) Result {
	scenes := input.Storyboard
	if len(scenes) == 0 {
		scenes = append([]Scene(nil), DefaultScenes...)
	}
	materials := NormalizeMaterials(input.Materials)
	text := strings.TrimSpace(input.ManualPrompt)
	if text == "" {
		if input.Mode == "image" {
			text = assembleImage(input, scenes)
		} else {
			text = assembleVideo(input, scenes)
		}
	}
	requirements := ExtractRequirements(text)
	warnings := []string{}
	available := Requirements{}
	for _, material := range materials {
		switch material.Type {
		case "video":
			available.Video++
		case "audio":
			available.Audio++
		default:
			available.Image++
		}
	}
	if requirements.Image > available.Image {
		warnings = append(warnings, fmt.Sprintf("提示词引用到 @图片%d，当前只绑定了 %d 张图片。", requirements.Image, available.Image))
	}
	if requirements.Video > available.Video {
		warnings = append(warnings, fmt.Sprintf("提示词引用到 @视频%d，当前只绑定了 %d 个视频。", requirements.Video, available.Video))
	}
	if requirements.Audio > available.Audio {
		warnings = append(warnings, fmt.Sprintf("提示词引用到 @音频%d，当前只绑定了 %d 个音频。", requirements.Audio, available.Audio))
	}
	return Result{Prompt: text, Scenes: scenes, Materials: materials, Warnings: warnings, Blocked: false, Requirements: requirements}
}

func NormalizeMaterials(input []Material) []Material {
	counters := map[string]int{"image": 0, "video": 0, "audio": 0}
	out := make([]Material, 0, len(input))
	for _, material := range input {
		if strings.TrimSpace(material.URL) == "" {
			continue
		}
		if material.Type != "image" && material.Type != "video" && material.Type != "audio" {
			material.Type = inferType(material.URL)
		}
		if material.Label == "" {
			counters[material.Type]++
			material.Label = label(material.Type, counters[material.Type])
		}
		out = append(out, material)
	}
	sort.SliceStable(out, func(i, j int) bool { return labelWeight(out[i].Label) < labelWeight(out[j].Label) })
	return out
}

var placeholderPattern = regexp.MustCompile(`@(参考视频|图片|图|视频|音频)([0-9]+)`)

func ExtractRequirements(text string) Requirements {
	result := Requirements{}
	for _, match := range placeholderPattern.FindAllStringSubmatch(text, -1) {
		var index int
		_, _ = fmt.Sscanf(match[2], "%d", &index)
		if index < 1 {
			continue
		}
		switch match[1] {
		case "视频", "参考视频":
			if index > result.Video {
				result.Video = index
			}
		case "音频":
			if index > result.Audio {
				result.Audio = index
			}
		default:
			if index > result.Image {
				result.Image = index
			}
		}
	}
	return result
}

func assembleImage(input Input, scenes []Scene) string {
	project := fallback(input.ProjectName, "当前项目")
	goal := fallback(input.ImageGoal, "生成可用于营销传播的主视觉图片")
	ratio := fallback(input.AspectRatio, "1:1")
	lines := []string{}
	for index, scene := range scenes {
		if index >= 4 {
			break
		}
		material := scene.MaterialLabel
		if material == "" {
			material = fmt.Sprintf("@图片%d", index+1)
		}
		suffix := ""
		if scene.Caption != "" {
			suffix = "；文字元素=" + scene.Caption
		}
		lines = append(lines, fmt.Sprintf("%d. %s：参考素材=%s；画面要点=%s%s", index+1, scene.Title, material, scene.Visual, suffix))
	}
	return fmt.Sprintf("营销图片生成。\n项目名称：%s\n目标：%s\n目标人群：%s\n表达重点：%s\n补充说明：%s\n整体风格真实、有设计感，适合品牌和社媒传播。\n素材引用：\n%s\n生成要求：\n- 严格参考提示词中的@图片素材，保持主体和关键信息一致。\n- 可以使用视频素材作为节奏、镜头或氛围参考，但最终输出单张图片。\n- 图片比例：%s。\n- 文字内容少而准确，避免错别字和无关标语。\n- 不额外添加与项目无关的信息。", project, fallback(input.ImageGoal, goal), fallback(input.Audience, "泛营销受众"), fallback(input.Offer, "突出产品、服务或活动核心卖点"), fallback(input.BrandLine, "保持干净、可信、可发布的视觉质感"), strings.Join(lines, "\n"), ratio)
}
func assembleVideo(input Input, scenes []Scene) string {
	info := []string{"项目名称：" + fallback(input.ProjectName, "当前项目")}
	if strings.TrimSpace(input.Audience) != "" {
		info = append(info, "目标人群："+strings.TrimSpace(input.Audience))
	}
	if strings.TrimSpace(input.Offer) != "" {
		info = append(info, "表达重点："+strings.TrimSpace(input.Offer))
	}
	if strings.TrimSpace(input.BrandLine) != "" {
		info = append(info, "补充说明："+strings.TrimSpace(input.BrandLine))
	}
	lines := []string{}
	for index, scene := range scenes {
		material := scene.MaterialLabel
		if material == "" {
			material = fmt.Sprintf("@图片%d", index+1)
		}
		suffix := ""
		if scene.Camera != "" {
			suffix += "；镜头=" + scene.Camera
		}
		if scene.HostLine != "" {
			suffix += "；口播=" + scene.HostLine
		}
		if scene.Caption != "" {
			suffix += "；字幕=" + scene.Caption
		}
		lines = append(lines, fmt.Sprintf("%d. %s：素材参考=%s；内容方向=%s%s", index+1, scene.Title, material, scene.Visual, suffix))
	}
	return fmt.Sprintf("通用营销宣传视频。\n参考风格：真实自然的营销宣传片，画面干净、节奏清楚、转场自然。\n%s\n内容结构：\n%s\n生成要求：\n- 以项目名称和@素材为准，不套用示例中的具体地点、人物、文案或品牌。\n- 图片素材用于控制主体、场景、商品和分镜；视频素材用于控制节奏、转场、运镜或参考风格。\n- 画面真实干净，主体清晰，转场自然，整体观感统一。\n- 如生成字幕，只保留简短标题或重点信息，避免大段文字。\n- 不额外添加与项目无关的信息。", strings.Join(info, "\n"), strings.Join(lines, "\n"))
}
func inferType(raw string) string {
	lower := strings.ToLower(strings.Split(raw, "?")[0])
	for _, suffix := range []string{".mp4", ".mov", ".webm"} {
		if strings.HasSuffix(lower, suffix) {
			return "video"
		}
	}
	for _, suffix := range []string{".mp3", ".wav", ".m4a", ".aac", ".flac"} {
		if strings.HasSuffix(lower, suffix) {
			return "audio"
		}
	}
	return "image"
}
func label(kind string, index int) string {
	if kind == "video" {
		return fmt.Sprintf("@视频%d", index)
	}
	if kind == "audio" {
		return fmt.Sprintf("@音频%d", index)
	}
	return fmt.Sprintf("@图片%d", index)
}
func labelWeight(value string) int {
	matches := regexp.MustCompile(`^@(图片|图|视频|音频)([0-9]+)$`).FindStringSubmatch(value)
	if len(matches) == 0 {
		return 999
	}
	var index int
	_, _ = fmt.Sscanf(matches[2], "%d", &index)
	base := 0
	if matches[1] == "视频" {
		base = 100
	} else if matches[1] == "音频" {
		base = 200
	}
	return base + index
}
func fallback(value, fallback string) string {
	if strings.TrimSpace(value) == "" {
		return fallback
	}
	return strings.TrimSpace(value)
}