package kiwix

// End-to-end score: Russian question -> model rewrite -> Kiwix search -> did a
// wanted article come back. Same 9 cases as the retrieval eval, so the two
// numbers are directly comparable: retrieval with hand-written keywords is the
// ceiling, this is what the model actually reaches.

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"
)

// RewriteOutcome — one case, end to end.
type RewriteOutcome struct {
	Outcome
	ModelQuery string // what the model asked for ("" if it failed)
	RewriteErr error
}

// RunRewriteEval rewrites every question with the model, then searches.
func RunRewriteEval(ctx context.Context, c *Client, rw *Rewriter, topN int) (RewriteReport, error) {
	var f fixture
	if err := json.Unmarshal(knowledgeFixtureJSON, &f); err != nil {
		return RewriteReport{}, err
	}
	rep := RewriteReport{Report: Report{Name: f.Name + "-rewrite", Book: f.Book, TopN: topN}}
	for _, cs := range f.Cases {
		out := RewriteOutcome{Outcome: Outcome{Case: cs}}
		q, err := rw.Rewrite(ctx, cs.Question)
		out.ModelQuery, out.RewriteErr = q, err
		if err == nil {
			res, serr := c.Search(ctx, q, f.Book, topN)
			out.Err = serr
			for i, hit := range res {
				out.Titles = append(out.Titles, hit.Title)
				if out.Rank == 0 && matches(cs.WantTitles, hit.Title) {
					out.Rank = i + 1
				}
			}
		}
		if out.RewriteErr != nil || out.Err != nil {
			rep.Errors++
		}
		if !cs.ExpectMiss {
			rep.Scored++
			if out.Hit() {
				rep.Hits++
			}
		}
		rep.Cases = append(rep.Cases, out)
	}
	return rep, nil
}

// RewriteReport — the score plus per-case detail.
type RewriteReport struct {
	Report
	Cases []RewriteOutcome
}

// String — the headline number.
func (r RewriteReport) String() string {
	return fmt.Sprintf("%s: %d/%d answerable questions retrieve a wanted article in top %d (%.1f%%), %d errors\n  book: %s\n",
		r.Name, r.Hits, r.Scored, r.TopN, 100*r.Accuracy(), r.Errors, r.Book)
}

// Detail — per case: hand-written query next to the model's, and what came back.
// The point is seeing WHERE the model's phrasing differs, not just the score.
func (r RewriteReport) Detail() string {
	var b strings.Builder
	for _, o := range r.Cases {
		mark := "MISS"
		switch {
		case o.Case.ExpectMiss:
			mark = "n/a "
		case o.Hit():
			mark = fmt.Sprintf("hit@%d", o.Rank)
		}
		fmt.Fprintf(&b, "  %-6s %-20s\n", mark, o.Case.ID)
		fmt.Fprintf(&b, "         asked:  %s\n", o.Case.Question)
		fmt.Fprintf(&b, "         hand:   %q\n", o.Case.Query)
		fmt.Fprintf(&b, "         model:  %q\n", o.ModelQuery)
		if o.RewriteErr != nil {
			fmt.Fprintf(&b, "         rewrite rejected: %v\n", o.RewriteErr)
			continue
		}
		if o.Err != nil {
			fmt.Fprintf(&b, "         search error: %v\n", o.Err)
			continue
		}
		fmt.Fprintf(&b, "         got:    %s\n", strings.Join(o.Titles, " | "))
	}
	return b.String()
}