package ecodash

import (
	"encoding/json"
	"errors"
	"fmt"
	"html"
	"html/template"
	"math"
	"os"
	"time"

	"git.massivebox.net/ecodash/ecodash/src/tools"
	"github.com/gofiber/fiber/v2"
)

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() fiber.Map {
	return fiber.Map{
		"DashboardName": config.Dashboard.Name,
		"HeaderLinks":   config.Dashboard.HeaderLinks,
		"FooterLinks":   config.Dashboard.FooterLinks,
	}
}

func (config *Config) TemplateDefaultsMap() fiber.Map {
	return fiber.Map{
		"Default": config.getTemplateDefaults(),
	}
}

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 {
				// #nosec the input is admin-defined, and the admin is assumed to be trusted.
				return config.RenderAdminPanel(c, &MessageCard{
					Title:   "An error occurred!",
					Content: template.HTML(html.EscapeString(err.Error())),
					Style:   "error",
				})
			}
			return config.RenderAdminPanel(c, &MessageCard{
				Title: "Settings applied",
				Content: "Your settings have been tested and <b>applied successfully</b>.<br>" +
					"You can continue using EcoDash on the <a href='./'>Home</a>.",
				Style: "success",
			})
		}

		// here the user is trying to authenticate
		if c.FormValue("username") == config.Administrator.Username && tools.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: tools.Hash(c.FormValue("password"))})
			return config.RenderAdminPanel(c, nil)
		}
		return c.Render("login", fiber.Map{"Defaults": config.getTemplateDefaults(), "Failed": true}, "base")
	}

	if config.IsAuthorized(c) {
		return config.RenderAdminPanel(c, nil)
	}
	return c.Render("login", config.TemplateDefaultsMap(), "base")
}

func (config *Config) RenderAdminPanel(c *fiber.Ctx, message *MessageCard) error {
	dirs, err := os.ReadDir("./templates")
	if err != nil {
		return err
	}

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

var (
	errNoChanges    = errors.New("no changes from previous config")
	errMissingField = errors.New("required field is missing")
)

func (config *Config) saveAdminForm(c *fiber.Ctx) error {
	requiredFields := []string{"base_url", "api_key", "polled_smart_energy_summation", "fossil_percentage", "username", "theme", "name", "installation_date"}
	for _, requiredField := range requiredFields {
		if c.FormValue(requiredField) == "" {
			return fmt.Errorf("%w: %s", errMissingField, requiredField)
		}
	}

	parsedTime, err := time.Parse("2006-01-02", c.FormValue("installation_date"))
	if err != nil {
		return err
	}

	form := Config{
		HomeAssistant: HomeAssistant{ /*BaseURL to be filled later*/ APIKey: c.FormValue("api_key"), InstallationDate: dayStart(parsedTime)},
		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 /*MessageCard to be filled later*/},
	}

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

	if c.FormValue("motd_title") != "" || c.FormValue("motd_content") != "" {
		// #nosec the input is admin-defined, and the admin is assumed to be trusted.
		form.Dashboard.MOTD = &MessageCard{
			Title:   c.FormValue("motd_title"),
			Content: template.HTML(c.FormValue("motd_content")),
			Style:   c.FormValue("motd_style"),
		}
	}

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

	if form.Equals(config) {
		return errNoChanges
	}

	form.db = config.db
	err = form.refreshCacheFromInstall()
	if err != nil {
		return err
	}

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

	*config = form
	return os.WriteFile("config.json", js, 0o600)
}

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

func (config *Config) RenderIndex(c *fiber.Ctx) error {
	if config.HomeAssistant.InstallationDate.IsZero() {
		return c.Render("config-error", fiber.Map{
			"Defaults": config.getTemplateDefaults(),
			"Error":    "The installation date is not set! This is normal if you've just updated from v0.1 to v0.2.",
		}, "base")
	}

	data, err := config.readHistory()
	if err != nil {
		return err
	}

	labels := make([]string, 0, len(data))
	greenEnergyConsumptionAbsolute := make([]float32, 0, len(data))
	greenEnergyPercents := make([]float32, 0, len(data))
	energyConsumptions := make([]float32, 0, len(data))

	for _, datum := range data {
		labels = append(labels, time.Unix(datum.Date, 0).Format("02/01"))
		greenEnergyPercents = append(greenEnergyPercents, datum.GreenEnergyPercentage)
		greenEnergyConsumptionAbsolute = append(greenEnergyConsumptionAbsolute, datum.GreenEnergyPercentage/100*datum.PolledSmartEnergySummation)
		energyConsumptions = append(energyConsumptions, datum.PolledSmartEnergySummation)
	}

	perDayUsage := averageExcludingCurrentDay(energyConsumptions)

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