package pkg

import (
	"context"
	"fmt"
	"github.com/julienschmidt/httprouter"
	"html/template"
	"math"
	"net/http"
	"strconv"
	"time"
)

type InvoiceEntry struct {
	Slug         string
	Date         time.Time
	Number       string
	CustomerName string
	CustomerSlug string
	Status       string
	StatusLabel  string
}

type InvoicesIndexPage struct {
	Invoices []*InvoiceEntry
}

func IndexInvoices(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
	page := &InvoicesIndexPage{
		Invoices: mustCollectInvoiceEntries(r.Context(), getConn(r), mustGetCompany(r), getLocale(r)),
	}
	mustRenderAppTemplate(w, r, "invoices/index.gohtml", page)
}

func mustCollectInvoiceEntries(ctx context.Context, conn *Conn, company *Company, locale *Locale) []*InvoiceEntry {
	rows := conn.MustQuery(ctx, "select invoice.slug, invoice_date, invoice_number, contact.business_name, contact.slug, invoice.invoice_status, isi18n.name from invoice join contact using (contact_id) join invoice_status_i18n isi18n on invoice.invoice_status = isi18n.invoice_status and isi18n.lang_tag = $2 where invoice.company_id = $1 order by invoice_date, invoice_number", company.Id, locale.Language.String())
	defer rows.Close()

	var entries []*InvoiceEntry
	for rows.Next() {
		entry := &InvoiceEntry{}
		if err := rows.Scan(&entry.Slug, &entry.Date, &entry.Number, &entry.CustomerName, &entry.CustomerSlug, &entry.Status, &entry.StatusLabel); err != nil {
			panic(err)
		}
		entries = append(entries, entry)
	}
	if rows.Err() != nil {
		panic(rows.Err())
	}

	return entries
}

func GetInvoiceForm(w http.ResponseWriter, r *http.Request, params httprouter.Params) {
	locale := getLocale(r)
	conn := getConn(r)
	company := mustGetCompany(r)
	form := newInvoiceForm(r.Context(), conn, locale, company)
	slug := params[0].Value
	if slug == "new" {
		form.Date.Val = time.Now().Format("2006-01-02")
		w.WriteHeader(http.StatusOK)
		mustRenderNewInvoiceForm(w, r, form)
		return
	}
}

func mustRenderNewInvoiceForm(w http.ResponseWriter, r *http.Request, form *invoiceForm) {
	locale := getLocale(r)
	form.Customer.EmptyLabel = gettext("Select a customer to bill.", locale)
	mustRenderAppTemplate(w, r, "invoices/new.gohtml", form)
}

func mustRenderNewInvoiceProductsForm(w http.ResponseWriter, r *http.Request, form *invoiceForm) {
	conn := getConn(r)
	company := mustGetCompany(r)
	page := newInvoiceProductsPage{
		Form:     form,
		Products: mustGetProductChoices(r.Context(), conn, company),
	}
	mustRenderAppTemplate(w, r, "invoices/products.gohtml", page)
}

func mustGetProductChoices(ctx context.Context, conn *Conn, company *Company) []*productChoice {
	rows := conn.MustQuery(ctx, "select product.product_id, product.name, to_price(price, decimal_digits) from product join company using (company_id) join currency using (currency_code) where company_id = $1 order by name", company.Id)
	defer rows.Close()

	var choices []*productChoice
	for rows.Next() {
		entry := &productChoice{}
		if err := rows.Scan(&entry.Id, &entry.Name, &entry.Price); err != nil {
			panic(err)
		}
		choices = append(choices, entry)
	}
	if rows.Err() != nil {
		panic(rows.Err())
	}

	return choices
}

type newInvoiceProductsPage struct {
	Form     *invoiceForm
	Products []*productChoice
}

type productChoice struct {
	Id    int
	Name  string
	Price string
}

func HandleAddInvoice(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
	locale := getLocale(r)
	conn := getConn(r)
	company := mustGetCompany(r)
	form := newInvoiceForm(r.Context(), conn, locale, company)
	if err := form.Parse(r); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	if err := verifyCsrfTokenValid(r); err != nil {
		http.Error(w, err.Error(), http.StatusForbidden)
		return
	}
	switch r.Form.Get("action") {
	case "update":
		form.Update()
		w.WriteHeader(http.StatusOK)
		mustRenderNewInvoiceForm(w, r, form)
	case "products":
		w.WriteHeader(http.StatusOK)
		mustRenderNewInvoiceProductsForm(w, r, form)
	case "add":
		if !form.Validate() {
			w.WriteHeader(http.StatusUnprocessableEntity)
			mustRenderNewInvoiceForm(w, r, form)
			return
		}
		conn.MustExec(r.Context(), "select add_invoice($1, $2, $3, $4, $5, $6)", company.Id, form.Number, form.Date, form.Customer, form.Notes, NewInvoiceProductArray(form.Products))
		http.Redirect(w, r, companyURI(company, "/invoices"), http.StatusSeeOther)
	default:
		http.Error(w, gettext("Invalid action", locale), http.StatusBadRequest)
	}
}

func HandleAddProductsToInvoice(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
	locale := getLocale(r)
	conn := getConn(r)
	company := mustGetCompany(r)
	form := newInvoiceForm(r.Context(), conn, locale, company)
	if err := form.Parse(r); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	index := len(form.Products)
	productsId := r.Form["id"]
	rows := conn.MustQuery(r.Context(), "select product_id, name, description, to_price(price, decimal_digits), 1 as quantity, 0 as discount, array_agg(tax_id) from product join company using (company_id) join currency using (currency_code) left join product_tax using (product_id) where product_id = any ($1) group by product_id, name, description, price, decimal_digits", productsId)
	defer rows.Close()
	for rows.Next() {
		product := newInvoiceProductForm(index, company, locale, form.Tax.Options)
		if err := rows.Scan(product.ProductId, product.Name, product.Description, product.Price, product.Quantity, product.Discount, product.Tax); err != nil {
			panic(err)
		}
		form.Products = append(form.Products, product)
		index++
	}
	if rows.Err() != nil {
		panic(rows.Err())
	}

	w.WriteHeader(http.StatusOK)
	mustRenderNewInvoiceForm(w, r, form)
}

type invoiceForm struct {
	locale   *Locale
	company  *Company
	Customer *SelectField
	Number   *InputField
	Date     *InputField
	Notes    *InputField
	Tax      *SelectField
	Products []*invoiceProductForm
}

func newInvoiceForm(ctx context.Context, conn *Conn, locale *Locale, company *Company) *invoiceForm {
	return &invoiceForm{
		locale:  locale,
		company: company,
		Customer: &SelectField{
			Name:     "customer",
			Label:    pgettext("input", "Customer", locale),
			Required: true,
			Options:  MustGetOptions(ctx, conn, "select contact_id::text, business_name from contact where company_id = $1 order by business_name", company.Id),
		},
		Number: &InputField{
			Name:     "number",
			Label:    pgettext("input", "Number", locale),
			Type:     "text",
			Required: false,
		},
		Date: &InputField{
			Name:     "date",
			Label:    pgettext("input", "Invoice Date", locale),
			Type:     "date",
			Required: true,
		},
		Notes: &InputField{
			Name:  "description",
			Label: pgettext("input", "Notes", locale),
			Type:  "textarea",
		},
		Tax: &SelectField{
			Name:     "text",
			Label:    pgettext("input", "Taxes", locale),
			Multiple: true,
			Options:  mustGetTaxOptions(ctx, conn, company),
		},
	}
}

func (form *invoiceForm) Parse(r *http.Request) error {
	if err := r.ParseForm(); err != nil {
		return err
	}
	form.Customer.FillValue(r)
	form.Number.FillValue(r)
	form.Date.FillValue(r)
	form.Notes.FillValue(r)
	if _, ok := r.Form["product.id.0"]; ok {
		for index := 0; true; index++ {
			if _, ok := r.Form["product.id."+strconv.Itoa(index)]; !ok {
				break
			}
			productForm := newInvoiceProductForm(index, form.company, form.locale, form.Tax.Options)
			if err := productForm.Parse(r); err != nil {
				return err
			}
			form.Products = append(form.Products, productForm)
		}
	}
	return nil
}

func (form *invoiceForm) Validate() bool {
	validator := newFormValidator()

	validator.CheckValidSelectOption(form.Customer, gettext("Name can not be empty.", form.locale))
	if validator.CheckRequiredInput(form.Date, gettext("Invoice date can not be empty.", form.locale)) {
		validator.CheckValidDate(form.Date, gettext("Invoice date must be a valid date.", form.locale))
	}
	validator.CheckValidSelectOption(form.Tax, gettext("Selected tax is not valid.", form.locale))

	allOK := validator.AllOK()
	for _, product := range form.Products {
		allOK = product.Validate() && allOK
	}
	return allOK
}

func (form *invoiceForm) Update() {
	products := form.Products
	form.Products = nil
	index := 0
	for _, product := range products {
		if product.Quantity.Val != "0" {
			form.Products = append(form.Products, product)
			index++
		}
	}
}

func mustGetTaxOptions(ctx context.Context, conn *Conn, company *Company) []*SelectOption {
	return MustGetOptions(ctx, conn, "select tax_id::text, name from tax where company_id = $1 order by name", company.Id)
}

type invoiceProductForm struct {
	locale      *Locale
	company     *Company
	ProductId   *InputField
	Name        *InputField
	Description *InputField
	Price       *InputField
	Quantity    *InputField
	Discount    *InputField
	Tax         *SelectField
}

func newInvoiceProductForm(index int, company *Company, locale *Locale, taxOptions []*SelectOption) *invoiceProductForm {
	suffix := "." + strconv.Itoa(index)
	return &invoiceProductForm{
		locale:  locale,
		company: company,
		ProductId: &InputField{
			Name:     "product.id" + suffix,
			Label:    pgettext("input", "Id", locale),
			Type:     "hidden",
			Required: true,
		},
		Name: &InputField{
			Name:     "product.name" + suffix,
			Label:    pgettext("input", "Name", locale),
			Type:     "text",
			Required: true,
		},
		Description: &InputField{
			Name:  "product.description" + suffix,
			Label: pgettext("input", "Description", locale),
			Type:  "textarea",
		},
		Price: &InputField{
			Name:     "product.price" + suffix,
			Label:    pgettext("input", "Price", locale),
			Type:     "number",
			Required: true,
			Attributes: []template.HTMLAttr{
				`min="0"`,
				template.HTMLAttr(fmt.Sprintf(`step="%v"`, company.MinCents())),
			},
		},
		Quantity: &InputField{
			Name:     "product.quantity" + suffix,
			Label:    pgettext("input", "Quantity", locale),
			Type:     "number",
			Required: true,
			Attributes: []template.HTMLAttr{
				`min="0"`,
			},
		},
		Discount: &InputField{
			Name:     "product.discount" + suffix,
			Label:    pgettext("input", "Discount (%)", locale),
			Type:     "number",
			Required: true,
			Attributes: []template.HTMLAttr{
				`min="0"`,
				`max="100"`,
			},
		},
		Tax: &SelectField{
			Name:     "product.tax" + suffix,
			Label:    pgettext("input", "Taxes", locale),
			Multiple: true,
			Options:  taxOptions,
		},
	}
}

func (form *invoiceProductForm) Parse(r *http.Request) error {
	if err := r.ParseForm(); err != nil {
		return err
	}
	form.ProductId.FillValue(r)
	form.Name.FillValue(r)
	form.Description.FillValue(r)
	form.Price.FillValue(r)
	form.Quantity.FillValue(r)
	form.Discount.FillValue(r)
	form.Tax.FillValue(r)
	return nil
}

func (form *invoiceProductForm) Validate() bool {
	validator := newFormValidator()
	validator.CheckRequiredInput(form.Name, gettext("Name can not be empty.", form.locale))
	if validator.CheckRequiredInput(form.Price, gettext("Price can not be empty.", form.locale)) {
		validator.CheckValidDecimal(form.Price, form.company.MinCents(), math.MaxFloat64, gettext("Price must be a number greater than zero.", form.locale))
	}
	if validator.CheckRequiredInput(form.Quantity, gettext("Quantity can not be empty.", form.locale)) {
		validator.CheckValidInteger(form.Quantity, 1, math.MaxInt32, gettext("Quantity must be a number greater than zero.", form.locale))
	}
	if validator.CheckRequiredInput(form.Discount, gettext("Discount can not be empty.", form.locale)) {
		validator.CheckValidInteger(form.Discount, 0, 100, gettext("Discount must be a percentage between 0 and 100.", form.locale))
	}
	validator.CheckValidSelectOption(form.Tax, gettext("Selected tax is not valid.", form.locale))
	return validator.AllOK()
}