package main

import (
	"encoding/json"
	"errors"
	"fmt"
	"github.com/gofiber/fiber/v2"
	"html/template"
	"math"
	"os"
	"reflect"
	"time"
)

type Link struct {
	Label       string `json:"label"`
	Destination string `json:"destination"`
	NewTab      bool   `json:"new_tab"`
	Primary     bool   `json:"primary"`
}

type Warning struct {
	Header    string
	Body      string
	BodyHTML  template.HTML
	IsSuccess bool
}

func (config Config) getTemplateDefaults() map[string]interface{} {
	return fiber.Map{
		"DashboardName": config.Dashboard.Name,
		"HeaderLinks":   config.Dashboard.HeaderLinks,
		"FooterLinks":   config.Dashboard.FooterLinks,
	}
}

func (config Config) adminEndpoint(c *fiber.Ctx) error {

	if c.Method() == "POST" {

		if config.isAuthorized(c) { // here the user is submitting the form to change configuration
			err := config.saveAdminForm(c)
			if err != nil {
				return config.renderAdminPanel(c, Warning{
					Header: "An error occurred!",
					Body:   err.Error(),
				})
			}
			return config.renderAdminPanel(c, Warning{
				Header: "Restart needed",
				Body: "In order to apply changes, please <b>restart EcoDash</b>.<br>" +
					"If you're running via Docker, click <a href='./restart'>here</a> to restart automatically.",
				IsSuccess: true,
			})
		}

		// here the user is trying to authenticate
		if c.FormValue("username") == config.Administrator.Username && hash(c.FormValue("password")) == config.Administrator.PasswordHash {
			c.Cookie(&fiber.Cookie{Name: "admin_username", Value: c.FormValue("username")})
			c.Cookie(&fiber.Cookie{Name: "admin_password_hash", Value: hash(c.FormValue("password"))})
			return config.renderAdminPanel(c)
		}
		return c.Render("login", fiber.Map{"Defaults": config.getTemplateDefaults(), "Failed": true}, "base")

	}

	if config.isAuthorized(c) {
		return config.renderAdminPanel(c)
	}
	return c.Render("login", fiber.Map{"Defaults": config.getTemplateDefaults()}, "base")

}

func (config Config) renderAdminPanel(c *fiber.Ctx, warning ...Warning) error {

	dirs, err := os.ReadDir("./templates")
	if err != nil {
		return err
	}

	if len(warning) > 0 {
		warning[0].BodyHTML = template.HTML(warning[0].Body)
		return c.Render("admin", fiber.Map{
			"Defaults": config.getTemplateDefaults(),
			"Themes":   dirs,
			"Config":   config,
			"Warning":  warning[0],
		}, "base")
	}

	return c.Render("admin", fiber.Map{
		"Defaults": config.getTemplateDefaults(),
		"Themes":   dirs,
		"Config":   config,
	}, "base")

}

func (config Config) saveAdminForm(c *fiber.Ctx) error {

	requiredFields := []string{"base_url", "api_key", "polled_smart_energy_summation", "fossil_percentage", "username", "theme", "name"}
	for _, requiredField := range requiredFields {
		if c.FormValue(requiredField) == "" {
			return errors.New("Required field is missing: " + requiredField)
		}
	}

	form := Config{
		HomeAssistant: HomeAssistant{ /*BaseURL to be filled later*/ ApiKey: c.FormValue("api_key")},
		Sensors:       Sensors{PolledSmartEnergySummation: c.FormValue("polled_smart_energy_summation"), FossilPercentage: c.FormValue("fossil_percentage")},
		Administrator: Administrator{Username: c.FormValue("username") /*PasswordHash to be filled later*/},
		Dashboard:     Dashboard{Theme: c.FormValue("theme"), Name: c.FormValue("name"), HeaderLinks: config.Dashboard.HeaderLinks, FooterLinks: config.Dashboard.FooterLinks},
	}

	if c.FormValue("keep_old_password") == "" {
		form.Administrator.PasswordHash = hash(c.FormValue("password"))
	} else {
		form.Administrator.PasswordHash = config.Administrator.PasswordHash
	}

	fmtURL, err := formatURL(c.FormValue("base_url"))
	if err != nil {
		return err
	}
	form.HomeAssistant.BaseURL = fmtURL

	if reflect.DeepEqual(form, config) {
		return errors.New("No changes from previous config.")
	}

	// in order to test if ha base URL, API key and entity IDs are correct we try fetching the devices history
	_, err = form.queryHistory(form.Sensors.FossilPercentage, time.Now().Add(-5*time.Minute), time.Now())
	if err != nil {
		return err
	}
	_, err = form.queryHistory(form.Sensors.PolledSmartEnergySummation, time.Now().Add(-5*time.Minute), time.Now())
	if err != nil {
		return err
	}

	js, err := json.Marshal(form)
	if err != nil {
		return err
	}

	return os.WriteFile("config.json", js, 0666)

}

func sevenDaysAverageExcludingCurrentDay(data []float32) float32 {
	if len(data) == 0 {
		return 0
	}
	data = data[:len(data)-1]
	var sum float32
	for _, num := range data {
		sum += num
	}
	var avg = sum / float32(len(data))
	return float32(math.Floor(float64(avg)*100)) / 100
}

func (config Config) renderIndex(c *fiber.Ctx) error {

	data, err := readCache()
	if err != nil {
		return err
	}

	var (
		labels                         []string
		greenEnergyConsumptionAbsolute []float32
		greenEnergyPercents            []float32
		energyConsumptions             []float32
	)

	for _, datum := range data {
		labels = append(labels, datum.Date)
		greenEnergyPercents = append(greenEnergyPercents, datum.GreenEnergyPercentage)
		greenEnergyConsumptionAbsolute = append(greenEnergyConsumptionAbsolute, datum.GreenEnergyPercentage/100*datum.PolledSmartEnergySummation)
		energyConsumptions = append(energyConsumptions, datum.PolledSmartEnergySummation)
	}

	perDayUsage := sevenDaysAverageExcludingCurrentDay(energyConsumptions)

	return c.Render("index", fiber.Map{
		"Defaults":            config.getTemplateDefaults(),
		"Labels":              labels,
		"GreenEnergyPercents": greenEnergyConsumptionAbsolute,
		"EnergyConsumptions":  energyConsumptions,
		"GreenEnergyPercent":  sevenDaysAverageExcludingCurrentDay(greenEnergyPercents),
		"PerDayUsage":         perDayUsage,
	}, "base")

}

func templateDivide(num1, num2 float32) template.HTML {
	var (
		isInDecimals     bool
		hasHitMeaningful bool
		meaningfulDigits int
		rounded          []byte
		num              = num1 / num2
	)
	for _, char := range []byte(fmt.Sprintf("%v", num)) {
		if (isInDecimals && char != '0') || hasHitMeaningful {
			hasHitMeaningful = true
			meaningfulDigits++
		}
		if char == '.' {
			isInDecimals = true
		}
		rounded = append(rounded, char)
		if meaningfulDigits == 3 {
			break
		}
	}
	return template.HTML(rounded)
}