package views

import (
	"bytes"
	"encoding/json"
	"fmt"
	"math"
	"regexp"
	"slices"
	"strings"

	"github.com/a-h/templ"
	"github.com/yuin/goldmark"
	"github.com/yuin/goldmark/extension"
	"github.com/yuin/goldmark/renderer/html"

	"git.b0b.be/bdeb/workout-suggester/internal/coach"
	"git.b0b.be/bdeb/workout-suggester/internal/routes"
	"git.b0b.be/bdeb/workout-suggester/internal/weather"
)

// md renders CommonMark + GFM. Raw HTML in model output is escaped
// (goldmark's default), so a reply can't inject markup into the page.
// Hard wraps: small models separate sections with single newlines.
var md = goldmark.New(goldmark.WithExtensions(extension.GFM), goldmark.WithRendererOptions(html.WithHardWraps()))

// sectionStart finds "**Label:**" lines. Models often start them right
// after a list, which Markdown would fold into the last bullet.
var sectionStart = regexp.MustCompile(`\n(\*\*[^*\n]+:?\*\*)`)

// Markdown renders model output as HTML, falling back to plain text.
func Markdown(src string) templ.Component {
	var buf bytes.Buffer
	src = sectionStart.ReplaceAllString(src, "\n\n$1")
	if err := md.Convert([]byte(src), &buf); err != nil {
		return Token(src)
	}
	return templ.Raw(buf.String())
}

func healthTrigger(h HealthInfo) string {
	if h.Checking {
		return "load"
	}
	return "every 30s"
}

func minutesLabel(m int) string {
	if m >= 60 && m%60 == 0 {
		return fmt.Sprintf("%dh", m/60)
	}
	if m > 60 {
		return fmt.Sprintf("%dh%02d", m/60, m%60)
	}
	return fmt.Sprintf("%d min", m)
}

func placeName(p string) string {
	if p == "" {
		return "📍 your location"
	}
	return p
}

// gustsLabel marks gusts that were estimated from wind speed.
func gustsLabel(f weather.Forecast) string {
	if f.GustsEstimated {
		return "≈"
	}
	return ""
}

func nextHours(f weather.Forecast, n int) []weather.Hour {
	return f.Hours[:min(n, len(f.Hours))]
}

func reasons(s coach.Score) string {
	if len(s.Reasons) == 0 {
		return "good conditions"
	}
	return strings.Join(s.Reasons, "; ")
}

// pickedReasons explains the pick's score, or why everything outside lost.
func pickedReasons(p coach.Plan) string {
	a := p.Assessment
	if a.Pick == coach.Indoor {
		var all []string
		for _, s := range a.Scores {
			for _, r := range s.Reasons {
				if !slices.Contains(all, r) {
					all = append(all, r)
				}
			}
		}
		return strings.Join(all, "; ")
	}
	if s := a.ScoreOf(a.Pick); len(s.Reasons) > 0 {
		return strings.Join(s.Reasons, "; ")
	}
	return ""
}

// loopDetails is the one-line summary of a generated loop.
func loopDetails(p coach.Plan, r *routes.Route) string {
	parts := []string{fmt.Sprintf("%d m climb", r.AscentM)}
	if r.PavedPct >= 0 {
		parts = append(parts, fmt.Sprintf("%d%% paved", r.PavedPct))
	}
	if r.IntoWind(p.Forecast.Now.WindDirection) {
		parts = append(parts, "into the wind first, tailwind home")
	}
	return strings.Join(parts, " · ")
}

func junctionKind(j *coach.JunctionInfo) string {
	if j.Kind == routes.Bike {
		return "cycling"
	}
	return "walking"
}

// mapData is the JSON the map script draws: you, the routes, the junction.
func mapData(p coach.Plan) string {
	type route struct {
		Name string         `json:"name"`
		Ways [][][2]float64 `json:"ways"`
		Join [2]float64     `json:"join"`
	}
	out := struct {
		You    [2]float64 `json:"you"`
		Routes []route    `json:"routes"`
	}{You: [2]float64{p.At.Lat, p.At.Lon}}
	for _, s := range p.Routes {
		r := route{Name: s.Route.Name, Join: [2]float64{s.JoinAt.Lat, s.JoinAt.Lon}}
		for _, w := range s.Route.Ways {
			pts := make([][2]float64, len(w))
			for i, q := range w {
				pts[i] = [2]float64{round5(q.Lat), round5(q.Lon)}
			}
			r.Ways = append(r.Ways, pts)
		}
		out.Routes = append(out.Routes, r)
	}
	b, _ := json.Marshal(out)
	return string(b)
}

func round5(v float64) float64 { return math.Round(v*1e5) / 1e5 }

// directionsURL opens OpenStreetMap's own (OSRM) directions from the user to
// where the route is closest.
func directionsURL(p coach.Plan, s routes.Suggestion) string {
	engine := "fossgis_osrm_foot"
	if s.Route.Kind == routes.Bike {
		engine = "fossgis_osrm_bike"
	}
	return fmt.Sprintf("https://www.openstreetmap.org/directions?engine=%s&route=%.5f%%2C%.5f%%3B%.5f%%2C%.5f",
		engine, p.At.Lat, p.At.Lon, s.JoinAt.Lat, s.JoinAt.Lon)
}