// Package scheduler 队列/调度角色：队列核心 + 能力路由 + 降级链 + 模版层整合
// （Contract §5-A3；模版层整合器归属 S7 P1-AR1 锁定）。
//
// template.go：共享模版层（整合器）。所有适配器的 RawResult 统一经此产出 Envelope：
// ① Size guard（markdown ≤ max_chars 截断 + truncated 标记）
// ② safetyscan（高危 block → error denied + audit；PII redact；注入包裹 wrap）
// ③ score 归一 0–1（searxng 位次分 1 - 0.05*rank 截断 [0,1]）
// ④ 信封封装（provenance.adapter/proxy_exit/cached/retrieved_at +08:00、
//
//	usage.tokens_estimate = ceil(chars/4)）。
//
// 合规代码零散在适配器内 = 门闩矩阵漂移，禁止。
package scheduler

import (
	"fmt"
	"strings"

	"onesvm.com/onesvm/browser-server/internal/contract"
	"onesvm.com/onesvm/browser-server/internal/safetyscan"
)

// maxContentSnippet 搜索 content 片段上限（mcp-usage §2.1：content ≤800 字符）。
const maxContentSnippet = 800

// Template 共享模版层。
type Template struct {
	scanner *safetyscan.Scanner
}

// NewTemplate 构造（词表加载失败即 error——fail-closed，不允许无扫描出结果）。
func NewTemplate() (*Template, error) {
	sc, err := safetyscan.Load()
	if err != nil {
		return nil, fmt.Errorf("scheduler: safetyscan 词表加载: %w", err)
	}
	return &Template{scanner: sc}, nil
}

// TemplateInput 模版层输入。
type TemplateInput struct {
	Job       contract.JobEnvelope
	Adapter   string // provenance.adapter
	ProxyExit string // direct | pool:<name> | none
	Cached    bool
	Raw       *contract.RawResult
	Warnings  []string // 降级链/引擎附加警示（降质必须显式打 warnings）
	TookMs    int64
}

// Build RawResult → Envelope。返回信封；safetyscan 高危命中时 ok=false +
// error=denied（合规拦截不假装成功，audit 由调用方落库）。
func (t *Template) Build(in TemplateInput) *contract.Envelope {
	env := &contract.Envelope{
		OK:        true,
		Kind:      in.Job.Intent,
		RequestID: in.Job.RequestID,
		TookMs:    in.TookMs,
	}
	warnings := in.Warnings
	if warnings == nil {
		warnings = []string{}
	}
	switch in.Job.Intent {
	case "search":
		sp, blocked := t.buildSearch(in, warnings)
		if blocked != nil {
			return blocked
		}
		env.Data = sp
		env.Usage = contract.Usage{Credits: 1, Engine: in.Raw.Engine,
			TokensEstimate: tokensEstimateOf(searchCharsOf(sp))}
	case "read":
		rp, blocked := t.buildRead(in, warnings)
		if blocked != nil {
			return blocked
		}
		env.Data = rp
		env.Usage = contract.Usage{Credits: 1, Engine: in.Raw.Engine,
			TokensEstimate: tokensEstimateOf(len([]rune(rp.Markdown)))}
	default:
		env.OK = false
		env.Error = &contract.ErrBody{Code: contract.CodeUpstream, Message: "未知意图 " + in.Job.Intent}
	}
	env.Provenance = contract.Provenance{
		URL:         in.Raw.FinalURL,
		FinalURL:    in.Raw.FinalURL,
		RetrievedAt: contract.NowTime(),
		Adapter:     in.Adapter,
		ProxyExit:   proxyExitOrDefault(in.ProxyExit),
		Cached:      in.Cached,
	}
	return env
}

// buildDenied 合规拦截信封（error.code=denied；不产数据块）。
func (t *Template) buildDenied(in TemplateInput, ruleID, reason string, warnings []string) *contract.Envelope {
	env := &contract.Envelope{
		OK:        false,
		Kind:      in.Job.Intent,
		RequestID: in.Job.RequestID,
		TookMs:    in.TookMs,
		Data:      nil,
		Error:     &contract.ErrBody{Code: contract.CodeDenied, Message: reason},
	}
	env.Provenance = contract.Provenance{
		RetrievedAt: contract.NowTime(),
		Adapter:     in.Adapter,
		ProxyExit:   proxyExitOrDefault(in.ProxyExit),
	}
	_ = warnings // 拦截信封无正文，warnings 随审计落库
	return env
}

// buildSearch kind=search 数据块：searxng 位次 → SearchResult（content ≤800 截断、
// score 归一、max_results 裁剪、published_at 东八区）。
func (t *Template) buildSearch(in TemplateInput, warnings []string) (*contract.SearchPayload, *contract.Envelope) {
	items, unres := parseSearxResults(in.Raw)
	if len(unres) > 0 {
		warnings = append(warnings, "unresponsive_engines: "+strings.Join(unres, ","))
	}
	payload := &contract.SearchPayload{Query: queryOf(in.Raw, in.Job), Results: []contract.SearchResult{}}
	max := 5
	if in.Job.Search != nil && in.Job.Search.MaxResults > 0 {
		max = in.Job.Search.MaxResults
	}
	if max > 20 {
		max = 20 // mcp-usage §2.1：≤20
	}
	for i, it := range items {
		if i >= max {
			break
		}
		res := contract.SearchResult{
			ID:      fmt.Sprintf("r%d", i+1),
			Title:   it.Title,
			URL:     it.URL,
			Content: clipRunes(it.Content, maxContentSnippet),
			Score:   normalizeRankScore(i),
			Engine:  it.Engine,
		}
		if it.PublishedDate != nil {
			if pt, ok := publishedAtOf(*it.PublishedDate); ok {
				res.PublishedAt = &pt
			}
		}
		payload.Results = append(payload.Results, res)
	}
	// ② safetyscan：title/content 逐条扫（search 无 markdown 字段）。
	for i := range payload.Results {
		res, outTitle, _, outMD := t.scanner.Scan(payload.Results[i].Title, "", payload.Results[i].Content)
		if res.Blocked {
			return nil, t.buildDenied(TemplateInput{Job: in.Job, Adapter: in.Adapter, TookMs: in.TookMs},
				res.WordlistVer, "搜索结果命中高危词表（wordlist "+res.WordlistVer+"）", res.Hits)
		}
		payload.Results[i].Title = outTitle
		payload.Results[i].Content = outMD
		if res.Redacted {
			warnings = append(warnings, "pii_redacted in search results")
		}
	}
	payload.EnsureEmptySlice()
	return payload, nil
}

// buildRead kind=read 数据块：size guard → safetyscan → 注入包裹。
func (t *Template) buildRead(in TemplateInput, warnings []string) (*contract.ReadPayload, *contract.Envelope) {
	in2 := in.Raw
	md := in2.Markdown
	if md == "" && in2.Text != "" {
		md = in2.Text // CDP 引擎 text 兜底
	}
	// ① Size guard：max_chars 截断 + truncated 显式标记。
	maxChars := 20000
	if in.Job.Read != nil && in.Job.Read.MaxChars > 0 {
		maxChars = in.Job.Read.MaxChars
	}
	truncated := false
	runes := []rune(md)
	if len(runes) > maxChars {
		md = string(runes[:maxChars])
		truncated = true
	}
	charCount := len([]rune(md))
	// ② safetyscan：title/description/markdown 分别扫。
	res, outTitle, _, outMD := t.scanner.Scan(in2.Title, "", md)
	if res.Blocked {
		return nil, t.buildDenied(TemplateInput{Job: in.Job, Adapter: in.Adapter, TookMs: in.TookMs},
			res.WordlistVer, "正文命中高危词表（wordlist "+res.WordlistVer+"）", res.Hits)
	}
	// ② 注入包裹：正文包 delimiter（防 ignore-previous-instructions）。
	wrapped := safetyscan.Wrap(outMD)
	if res.Redacted {
		warnings = append(warnings, fmt.Sprintf("pii_redacted (%d 处)", res.RedactCount))
	}
	rp := &contract.ReadPayload{
		URL:       firstNonEmptyStr(readURLof(in.Job), in2.FinalURL),
		FinalURL:  in2.FinalURL,
		Title:     outTitle,
		Markdown:  wrapped,
		Truncated: truncated,
		CharCount: charCount,
		Metadata: contract.ReadMetadata{
			StatusCode:  in2.StatusCode,
			ContentType: contentTypeOf(in2),
			Language:    "",
			RetrievedAt: contract.NowTime(),
		},
		Links:     []string{},
		Images:    []string{},
		Warnings:  warnings,
		Extracted: nil,
	}
	rp.EnsureEmptySlice()
	return rp, nil
}

// normalizeRankScore 位次分归一（plan-final §2.5 / A3.2：1 - 0.05*rank 截断 [0,1]）。
func normalizeRankScore(rank int) float64 {
	s := 1 - 0.05*float64(rank)
	if s < 0 {
		s = 0
	}
	if s > 1 {
		s = 1
	}
	return s
}

// tokensEstimate usage.tokens_estimate = ceil(chars/4)。
func tokensEstimateOf(chars int) int {
	if chars <= 0 {
		return 0
	}
	return (chars + 3) / 4
}

func searchCharsOf(p *contract.SearchPayload) int {
	n := 0
	for _, r := range p.Results {
		n += len([]rune(r.Title + r.Content))
	}
	return n
}

func proxyExitOrDefault(p string) string {
	if p == "" {
		return "none"
	}
	return p
}

func clipRunes(s string, n int) string {
	r := []rune(s)
	if len(r) <= n {
		return s
	}
	return string(r[:n])
}

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

func queryOf(raw *contract.RawResult, job contract.JobEnvelope) string {
	if q, ok := raw.Extra["query"].(string); ok && q != "" {
		return q
	}
	if job.Search != nil {
		return job.Search.Query
	}
	return ""
}

func readURLof(job contract.JobEnvelope) string {
	if job.Read != nil {
		return job.Read.URL
	}
	return ""
}

func contentTypeOf(raw *contract.RawResult) string {
	if ct, ok := raw.Extra["content_type"].(string); ok {
		return ct
	}
	if raw.StatusCode >= 200 && raw.StatusCode < 300 {
		return "text/html"
	}
	return ""
}