package semantic

import (
	"context"
	"fmt"
	"math"
	"sort"
	"strings"
	"time"

	"github.com/kami/maven/internal/router"
)

// ScoreLegacy runs the actual router against the corpus and produces the
// baseline report. The now parameter is the reference clock for relative
// time expressions.
func ScoreLegacy(ctx context.Context, r LegacyRouter, exs []RouteExample, now time.Time) LegacyReport {
	stats := CorpusStatsFrom(exs)
	rep := LegacyReport{
		Stats:    stats,
		Total:    len(exs),
		ByRoute:  make(map[SemanticRoute]RouteMetrics),
		Confusion: make(map[SemanticRoute]map[SemanticRoute]int),
	}
	for _, rt := range AllRoutes {
		rep.Confusion[rt] = make(map[SemanticRoute]int)
	}

	for _, e := range exs {
		input := router.NormalizedInput{Text: e.Text}
		d, err := r.Route(ctx, input, now)
		var predicted SemanticRoute
		var fpHit bool
		var preroute bool
		if err != nil {
			predicted = RouteUncertain
		} else {
			// Determine if fast-path resolved this.
			fpHit = d.Stage == 0 && d.Producer == router.RouteProducerGrammar
			predicted = IntentToRoute(d.Intent)
			// Pre-route consumption: command-prohibition grammar emits
			// IntentAct with Fn=prohibited_act at stage 0. These cases
			// never reach the general cascade.
			preroute = d.Stage == 0 && d.Slots.Fn == "prohibited_act"
		}
		agree := predicted == e.Route
		c := LegacyCase{
			Example:          e,
			Decision:         d,
			Predicted:        predicted,
			Agree:            agree,
			FastPathHit:      fpHit,
			PrerouteConsumed: preroute,
			Error:            err,
		}
		rep.Cases = append(rep.Cases, c)

		rep.Confusion[e.Route][predicted]++
		if agree {
			rep.Passed++
		}
		if e.Route != RouteAction && predicted == RouteAction {
			rep.FalseAction++
			rep.FalseActionCases = append(rep.FalseActionCases, c)
		}
		if e.FastPathResolved || fpHit {
			if preroute {
				// Command-prohibition grammar: consumed before cascade.
				rep.PreRouteTotal++
				if agree {
					rep.PreRoutePassed++
				}
			} else {
				rep.FastPathTotal++
				if agree {
					rep.FastPathPassed++
				}
			}
		} else {
			rep.ResidualTotal++
			if agree {
				rep.ResidualPassed++
			}
			// All residual cases are router-residual (the learned
			// router would see all of them).
			rep.RouterResidualTotal++
			if agree {
				rep.RouterResidualPassed++
			}
		}
	}

	if rep.Total > 0 {
		rep.FalseActionRate = float64(rep.FalseAction) / float64(rep.Total)
	}

	// Per-route P/R/F1.
	for _, route := range AllRoutes {
		tp, fp, fn := 0, 0, 0
		for _, got := range AllRoutes {
			count := rep.Confusion[route][got]
			if got == route {
				tp = count
			} else {
				fn += count
				fp += rep.Confusion[got][route]
			}
		}
		rm := RouteMetrics{TP: tp, FP: fp, FN: fn}
		if tp+fp > 0 {
			rm.Precision = float64(tp) / float64(tp+fp)
		}
		if tp+fn > 0 {
			rm.Recall = float64(tp) / float64(tp+fn)
		}
		if rm.Precision+rm.Recall > 0 {
			rm.F1 = 2 * rm.Precision * rm.Recall / (rm.Precision + rm.Recall)
		}
		rm.F1 = math.Round(rm.F1*1000) / 1000
		rm.Precision = math.Round(rm.Precision*1000) / 1000
		rm.Recall = math.Round(rm.Recall*1000) / 1000
		rep.ByRoute[route] = rm
	}

	return rep
}

// MacroF1 returns the macro-averaged F1 across all routes.
func (r LegacyReport) MacroF1() float64 {
	if len(r.ByRoute) == 0 {
		return 0
	}
	var sum float64
	for _, rm := range r.ByRoute {
		sum += rm.F1
	}
	return math.Round(sum/float64(len(r.ByRoute))*1000) / 1000
}

// String renders the legacy baseline report.
func (r LegacyReport) String() string {
	var b strings.Builder
	fmt.Fprintf(&b, "legacy baseline: %d/%d (%.1f%%)\n", r.Passed, r.Total,
		100*float64(r.Passed)/math.Max(float64(r.Total), 1))
	fmt.Fprintf(&b, "  macro F1: %.3f\n", r.MacroF1())
	fmt.Fprintf(&b, "  false-action: %d/%d (%.3f)\n", r.FalseAction, r.Total, r.FalseActionRate)
	fmt.Fprintf(&b, "  fast-path: %d/%d  residual: %d/%d\n",
		r.FastPathPassed, r.FastPathTotal,
		r.ResidualPassed, r.ResidualTotal)
	if r.RouterResidualTotal > 0 {
		fmt.Fprintf(&b, "  router-residual: %d/%d  (pre-route consumed: %d)\n",
			r.RouterResidualPassed, r.RouterResidualTotal, r.PreRouteTotal)
	}
	fmt.Fprintf(&b, "  per-route:\n")
	routes := make([]SemanticRoute, 0, len(r.ByRoute))
	for route := range r.ByRoute {
		routes = append(routes, route)
	}
	sort.Slice(routes, func(i, j int) bool { return routes[i] < routes[j] })
	for _, route := range routes {
		rm := r.ByRoute[route]
		fmt.Fprintf(&b, "    %-15s P=%.3f R=%.3f F1=%.3f  (tp=%d fp=%d fn=%d)\n",
			string(route), rm.Precision, rm.Recall, rm.F1, rm.TP, rm.FP, rm.FN)
	}
	fmt.Fprintf(&b, "  confusion matrix:\n")
	fmt.Fprintf(&b, "    %-15s", "")
	for _, g := range routes {
		fmt.Fprintf(&b, " %12s", string(g))
	}
	fmt.Fprintf(&b, "\n")
	for _, w := range routes {
		fmt.Fprintf(&b, "    %-15s", string(w))
		for _, g := range routes {
			fmt.Fprintf(&b, " %12d", r.Confusion[w][g])
		}
		fmt.Fprintf(&b, "\n")
	}
	if len(r.FalseActionCases) > 0 {
		fmt.Fprintf(&b, "  false-action cases:\n")
		for _, c := range r.FalseActionCases {
			decided := "(error)"
			if c.Error == nil {
				decided = fmt.Sprintf("%s (%.3f)", c.Decision.Intent, c.Decision.Confidence)
			}
			fmt.Fprintf(&b, "    %s %q: expected %s, got action (decided %s)\n",
				c.Example.SourceID, c.Example.Text, c.Example.Route, decided)
		}
	}
	return b.String()
}

// ContrastFamilies splits the corpus rows by their transform tag and reports
// per-family performance against the legacy router.
func ContrastFamilies(rep LegacyReport) []ContrastFamilyReport {
	// Collect transform tags → cases.
	tagCases := map[string][]LegacyCase{}
	for _, c := range rep.Cases {
		for _, tag := range c.Example.Tags {
			switch tag {
			case "negation", "question", "reported_speech", "quotation",
				"hypothetical", "capability_question":
				tagCases[tag] = append(tagCases[tag], c)
			}
		}
	}

	var reports []ContrastFamilyReport
	for _, tag := range []string{
		"negation", "question", "reported_speech", "quotation",
		"hypothetical", "capability_question",
	} {
		cases := tagCases[tag]
		if len(cases) == 0 {
			continue
		}
		cr := ContrastFamilyReport{Transform: tag, Examples: len(cases), Cases: cases}
		for _, c := range cases {
			if c.Agree {
				cr.Correct++
			}
			if c.Example.Route != RouteAction && c.Predicted == RouteAction {
				cr.FalseAction++
			} else if !c.Agree {
				cr.OtherErrors++
			}
		}
		reports = append(reports, cr)
	}
	return reports
}

// String renders the contrast family report.
func ContrastFamilyReportString(r []ContrastFamilyReport) string {
	var b strings.Builder
	fmt.Fprintf(&b, "%-20s %8s %8s %8s %8s\n", "transform", "examples", "correct", "false-act", "other")
	for _, cr := range r {
		fmt.Fprintf(&b, "%-20s %8d %8d %8d %8d\n",
			cr.Transform, cr.Examples, cr.Correct, cr.FalseAction, cr.OtherErrors)
	}
	return b.String()
}