// Package reporttemplate provides embedded Markdown templates and partials.
package reporttemplate

import (
	"bytes"
	"embed"
	"fmt"
	"text/template"
)

//go:embed templates/*.md.tmpl templates/partials/*.md.tmpl
var assets embed.FS

var templates = map[string]string{
	"daily":    "templates/daily.md.tmpl",
	"hourly":   "templates/hourly.md.tmpl",
	"today":    "templates/today.md.tmpl",
	"tomorrow": "templates/tomorrow.md.tmpl",
}

var templatePartials = []string{
	"templates/partials/alert_digest.md.tmpl",
	"templates/partials/daypart_forecast.md.tmpl",
	"templates/partials/precipitation_timing.md.tmpl",
	"templates/partials/today_daypart_forecast.md.tmpl",
}

func Template(id string) (string, error) {
	path, ok := templates[id]
	if !ok {
		return "", fmt.Errorf("unknown report template %q", id)
	}
	data, err := assets.ReadFile(path)
	if err != nil {
		return "", fmt.Errorf("read report template %q: %w", id, err)
	}
	return string(data), nil
}

func Render(id string, data any) ([]byte, error) {
	source, err := Template(id)
	if err != nil {
		return nil, err
	}
	tmpl, err := template.New(id).Funcs(templateFuncs()).Option("missingkey=error").Parse(source)
	if err != nil {
		return nil, fmt.Errorf("parse report template %q: %w", id, err)
	}
	for _, path := range templatePartials {
		partial, err := assets.ReadFile(path)
		if err != nil {
			return nil, fmt.Errorf("read report template partial %q: %w", path, err)
		}
		tmpl, err = tmpl.Parse(string(partial))
		if err != nil {
			return nil, fmt.Errorf("parse report template partial %q: %w", path, err)
		}
	}
	var out bytes.Buffer
	if err := tmpl.Execute(&out, data); err != nil {
		return nil, fmt.Errorf("render report template %q: %w", id, err)
	}
	return out.Bytes(), nil
}