package processing

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"log"
	"strings"
	"time"
)

// enhanceLogHeadTail caps each end of prompt/response bodies in worker logs.
const enhanceLogHeadTail = 500

func emptyLogDash(s string) string {
	s = strings.TrimSpace(s)
	if s == "" {
		return "-"
	}
	return s
}

// truncateLogEnds returns a PII-safe preview: total rune length plus first/last
// slices when the body is large (avoids megabyte log lines).
func truncateLogEnds(s string, head, tail int) string {
	s = strings.TrimSpace(s)
	if s == "" {
		return "len=0"
	}
	runes := []rune(s)
	n := len(runes)
	if head < 0 {
		head = 0
	}
	if tail < 0 {
		tail = 0
	}
	if n <= head+tail+32 {
		return fmt.Sprintf("len=%d body=%q", n, s)
	}
	return fmt.Sprintf("len=%d head=%q tail=%q", n, string(runes[:head]), string(runes[n-tail:]))
}

// formulaTemplateSummary summarizes a category title/description formula for logs
// (section/element types + JSON byte length + short content hash — not a full dump).
func formulaTemplateSummary(template any, kind string) string {
	if template == nil {
		return "none"
	}
	raw, err := json.Marshal(template)
	if err != nil || len(raw) == 0 || string(raw) == "null" || string(raw) == "{}" {
		return "none"
	}
	sum := sha256.Sum256(raw)
	hash8 := hex.EncodeToString(sum[:4])
	switch kind {
	case "title":
		els, sep, ok := parseTitleFormula(template)
		if !ok {
			return fmt.Sprintf("unparsed len=%d hash=%s", len(raw), hash8)
		}
		types := make([]string, 0, len(els))
		for _, el := range els {
			types = append(types, el.Type)
		}
		return fmt.Sprintf("elements=%s sep=%q len=%d hash=%s", strings.Join(types, "+"), sep, len(raw), hash8)
	case "description":
		sections, ok := parseDescriptionFormulaSections(template)
		if !ok {
			return fmt.Sprintf("unparsed len=%d hash=%s", len(raw), hash8)
		}
		types := make([]string, 0, len(sections))
		for _, sec := range sections {
			if t := strings.TrimSpace(sec.Type); t != "" {
				types = append(types, t)
			}
		}
		return fmt.Sprintf("sections=%s len=%d hash=%s", strings.Join(types, "+"), len(raw), hash8)
	default:
		return fmt.Sprintf("len=%d hash=%s", len(raw), hash8)
	}
}

func finishReasonFromCompletion(comp Completion) string {
	m, ok := comp.Raw.(map[string]any)
	if !ok || m == nil {
		return ""
	}
	fr, _ := m["finish_reason"].(string)
	return strings.TrimSpace(fr)
}

func enhanceFormulaOverride(in ProductInput) bool {
	return FormatDescriptionFormulaConstraint(in.DescriptionTemplate) != "" ||
		FormatTitleFormulaConstraint(in.TitleTemplate) != ""
}

// logEnhancePrompt emits one structured line before the LLM call (truncated prompts).
func logEnhancePrompt(in ProductInput, categoryUID, categoryName, system, user string) {
	log.Printf("processing: ai_enhance prompt job=%s company=%s raw=%s category_uid=%q category_name=%q title_formula=%s desc_formula=%s formula_override=%t system=%s user=%s",
		emptyLogDash(in.JobID), emptyLogDash(in.CompanyID), emptyLogDash(in.RawProductID),
		strings.TrimSpace(categoryUID), strings.TrimSpace(categoryName),
		formulaTemplateSummary(in.TitleTemplate, "title"),
		formulaTemplateSummary(in.DescriptionTemplate, "description"),
		enhanceFormulaOverride(in),
		truncateLogEnds(system, enhanceLogHeadTail, enhanceLogHeadTail),
		truncateLogEnds(user, enhanceLogHeadTail, enhanceLogHeadTail),
	)
}

// logEnhanceOutcome emits one structured line for the enhance result (truncated response).
func logEnhanceOutcome(in ProductInput, categoryUID, categoryName, outcome, reason string, comp Completion, elapsed time.Duration, forceReason string) {
	log.Printf("processing: ai_enhance outcome=%s reason=%s job=%s company=%s raw=%s category_uid=%q category_name=%q title_formula=%s desc_formula=%s formula_override=%t finish_reason=%s prompt_tokens=%d completion_tokens=%d total_tokens=%d elapsed=%s response=%s force_reason=%s",
		emptyLogDash(outcome), emptyLogDash(reason),
		emptyLogDash(in.JobID), emptyLogDash(in.CompanyID), emptyLogDash(in.RawProductID),
		strings.TrimSpace(categoryUID), strings.TrimSpace(categoryName),
		formulaTemplateSummary(in.TitleTemplate, "title"),
		formulaTemplateSummary(in.DescriptionTemplate, "description"),
		enhanceFormulaOverride(in),
		emptyLogDash(finishReasonFromCompletion(comp)),
		comp.PromptTokens, comp.OutputTokens, comp.TotalTokens,
		elapsed.Round(time.Millisecond),
		truncateLogEnds(comp.Text, enhanceLogHeadTail, enhanceLogHeadTail),
		emptyLogDash(forceReason),
	)
}