package cmd

import (
	"fmt"
	"os"

	"github.com/kb-search/kb/internal/api"
	"github.com/kb-search/kb/internal/output"
	"github.com/spf13/cobra"
)

var searchCmd = &cobra.Command{
	Use:   "search <query>",
	Short: "Search the knowledge base",
	Args:  cobra.ExactArgs(1),
	RunE:  runSearch,
}

func init() {
	searchCmd.Flags().IntP("top", "n", 10, "number of results to return")
	searchCmd.Flags().String("tags", "", "filter by tags (comma-separated)")
	searchCmd.Flags().String("type", "", "filter by document type")
	searchCmd.Flags().Bool("fts-only", false, "use full-text search only")
	searchCmd.Flags().Bool("vec-only", false, "use vector search only")
	searchCmd.Flags().Float64("threshold", 0, "minimum score threshold")
	searchCmd.Flags().Bool("explain", false, "include per-result score breakdown")
	searchCmd.Flags().Bool("no-rerank", false, "skip cross-encoder reranking (lower latency)")
	rootCmd.AddCommand(searchCmd)
}

func runSearch(cmd *cobra.Command, args []string) error {
	top, _ := cmd.Flags().GetInt("top")
	tags, _ := cmd.Flags().GetString("tags")
	docType, _ := cmd.Flags().GetString("type")
	ftsOnly, _ := cmd.Flags().GetBool("fts-only")
	vecOnly, _ := cmd.Flags().GetBool("vec-only")
	threshold, _ := cmd.Flags().GetFloat64("threshold")
	explain, _ := cmd.Flags().GetBool("explain")
	noRerank, _ := cmd.Flags().GetBool("no-rerank")

	body := map[string]interface{}{
		"query": args[0],
		"top":   top,
	}
	if tags != "" {
		body["tags"] = splitTags(tags)
	}
	if docType != "" {
		body["doc_type"] = docType
	}
	if ftsOnly {
		body["fts_only"] = true
	}
	if vecOnly {
		body["vec_only"] = true
	}
	if threshold > 0 {
		body["threshold"] = threshold
	}
	if explain {
		body["explain"] = true
	}
	if noRerank {
		body["rerank"] = false
	}

	client := api.NewClient()
	resp, err := client.Post("/api/v1/search", body)
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	if err := api.CheckError(resp); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}

	var result struct {
		Reranked bool `json:"reranked"`
		Results  []struct {
			Score         float64                `json:"score"`
			DocumentID    int64                  `json:"document_id"`
			Title         string                 `json:"title"`
			DocType       string                 `json:"doc_type"`
			Tags          []string               `json:"tags"`
			TagContexts   map[string]string      `json:"tag_contexts"`
			ChunkMetadata map[string]interface{} `json:"chunk_metadata"`
			Text          string                 `json:"text"`
			Explain       map[string]interface{} `json:"explain"`
		} `json:"results"`
	}

	if output.IsJSON() {
		var raw interface{}
		if err := api.DecodeJSON(resp, &raw); err != nil {
			return fmt.Errorf("failed to decode response: %w", err)
		}
		output.PrintJSON(raw)
		return nil
	}

	if err := api.DecodeJSON(resp, &result); err != nil {
		return fmt.Errorf("failed to decode response: %w", err)
	}

	if len(result.Results) == 0 {
		fmt.Println("No results found.")
		return nil
	}

	if result.Reranked {
		fmt.Println("(reranked)")
	}

	for i, r := range result.Results {
		snippet := r.Text
		if len(snippet) > 200 {
			snippet = snippet[:200] + "..."
		}

		fmt.Printf("\n%d. [%.4f] %s (doc:%d)\n", i+1, r.Score, r.Title, r.DocumentID)

		location := ""
		if page, ok := r.ChunkMetadata["page"]; ok && page != nil {
			location = fmt.Sprintf("Page %v", page)
		}
		if section, ok := r.ChunkMetadata["section_header"]; ok && section != nil {
			if s, ok := section.(string); ok && s != "" {
				if location != "" {
					location += " / "
				}
				location += s
			}
		}
		if location != "" {
			fmt.Printf("   Location: %s\n", location)
		}
		if r.DocType != "" {
			fmt.Printf("   Type: %s\n", r.DocType)
		}
		if len(r.Tags) > 0 {
			fmt.Printf("   Tags: %s\n", joinStrings(r.Tags))
		}
		for _, tag := range r.Tags {
			if desc, ok := r.TagContexts[tag]; ok && desc != "" {
				fmt.Printf("   Context: %s — %s\n", tag, desc)
			}
		}
		if r.Explain != nil {
			fmt.Printf("   Score: %s\n", formatExplain(r.Explain))
		}
		fmt.Printf("   %s\n", snippet)
	}
	fmt.Println()
	return nil
}

// formatExplain renders the engine's explain breakdown as one line, e.g.
// "fts score=4.213 rank=2 (rrf 0.016129) | vec score=0.512 rank=1 (rrf 0.016393) | bonus 0.05 | final 0.082522"
func formatExplain(e map[string]interface{}) string {
	num := func(key string) (float64, bool) {
		v, ok := e[key].(float64)
		return v, ok
	}
	var parts []string
	for _, arm := range []string{"fts", "vec"} {
		score, hasScore := num(arm + "_score")
		if !hasScore {
			continue
		}
		part := fmt.Sprintf("%s score=%.4f", arm, score)
		if rank, ok := num(arm + "_rank"); ok {
			part += fmt.Sprintf(" rank=%d", int(rank))
		}
		if rrf, ok := num("rrf_" + arm); ok {
			part += fmt.Sprintf(" (rrf %.6f)", rrf)
		}
		parts = append(parts, part)
	}
	if bonus, ok := num("bonus"); ok && bonus > 0 {
		parts = append(parts, fmt.Sprintf("bonus %.2f", bonus))
	}
	for _, key := range []string{"pre_rerank_rank", "rerank_score", "blend_weight"} {
		if v, ok := num(key); ok {
			parts = append(parts, fmt.Sprintf("%s %.4f", key, v))
		}
	}
	if final, ok := num("final_score"); ok {
		parts = append(parts, fmt.Sprintf("final %.6f", final))
	}
	result := ""
	for i, p := range parts {
		if i > 0 {
			result += " | "
		}
		result += p
	}
	return result
}

func joinStrings(ss []string) string {
	result := ""
	for i, s := range ss {
		if i > 0 {
			result += ", "
		}
		result += s
	}
	return result
}