package bakeoff

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

// MedianReadability combines several scorer replies: each score is the
// median across replies, and the notes come from the reply whose overall
// score is the median. Replies may wrap the JSON in a code fence.
func MedianReadability(replies []string) (Readability, error) {
	type reply struct {
		Naming, Structure, Traceability, Errors, Comments, Overall float64
		Notes                                                      string
	}
	var rs []reply
	for _, s := range replies {
		i, j := strings.Index(s, "{"), strings.LastIndex(s, "}")
		if i < 0 || j < i {
			return Readability{}, fmt.Errorf("no JSON object in reply %q", s)
		}
		var r reply
		if err := json.Unmarshal([]byte(s[i:j+1]), &r); err != nil {
			return Readability{}, err
		}
		rs = append(rs, r)
	}
	if len(rs) == 0 {
		return Readability{}, fmt.Errorf("no replies")
	}
	med := func(get func(reply) float64) float64 {
		v := make([]float64, len(rs))
		for i, r := range rs {
			v[i] = get(r)
		}
		return median(v)
	}
	out := Readability{
		Naming:       med(func(r reply) float64 { return r.Naming }),
		Structure:    med(func(r reply) float64 { return r.Structure }),
		Traceability: med(func(r reply) float64 { return r.Traceability }),
		Errors:       med(func(r reply) float64 { return r.Errors }),
		Comments:     med(func(r reply) float64 { return r.Comments }),
		Overall:      med(func(r reply) float64 { return r.Overall }),
	}
	byOverall := append([]reply(nil), rs...)
	sort.SliceStable(byOverall, func(i, j int) bool { return byOverall[i].Overall < byOverall[j].Overall })
	out.Notes = byOverall[len(byOverall)/2].Notes
	return out, nil
}