package api

import (
	"context"
	"errors"
	"net/http"
	"strings"
	"time"

	"gardomatic.kleiax.de/internal/auth"
	"gardomatic.kleiax.de/internal/platform/validate"
	"gardomatic.kleiax.de/internal/storage"
	"github.com/julienschmidt/httprouter"
)

type accountSession struct {
	ID        string    `json:"id"`
	CreatedAt time.Time `json:"created_at"`
	ExpiresAt time.Time `json:"expires_at"`
	Current   bool      `json:"current"`
}

func (app *application) listAccountSessionsHandler(w http.ResponseWriter, r *http.Request) {
	user, _ := app.contextGetAuthenticatedUser(r)
	currentID := app.sessions.GetString(r.Context(), accountSessionIDKey)
	sessions := make([]accountSession, 0)
	err := app.sessions.Iterate(r.Context(), func(ctx context.Context) error {
		if app.sessions.GetInt(ctx, authenticatedUserIDSessionKey) != user.ID {
			return nil
		}
		id := app.sessions.GetString(ctx, accountSessionIDKey)
		if id == "" {
			return nil
		}
		sessions = append(sessions, accountSession{
			ID:        id,
			CreatedAt: time.Unix(app.sessions.GetInt64(ctx, accountSessionCreatedAtKey), 0).UTC(),
			ExpiresAt: app.sessions.Deadline(ctx),
			Current:   id == currentID,
		})
		return nil
	})
	if err != nil {
		app.serverErrorResponse(w, r, err)
		return
	}
	if err = app.writeJSON(w, http.StatusOK, envelope{"sessions": sessions}, nil); err != nil {
		app.serverErrorResponse(w, r, err)
	}
}

func (app *application) deleteAccountSessionHandler(w http.ResponseWriter, r *http.Request) {
	user, _ := app.contextGetAuthenticatedUser(r)
	targetID := httprouter.ParamsFromContext(r.Context()).ByName("sessionID")
	if targetID == app.sessions.GetString(r.Context(), accountSessionIDKey) {
		if err := app.sessions.Destroy(r.Context()); err != nil {
			app.serverErrorResponse(w, r, err)
			return
		}
		w.WriteHeader(http.StatusNoContent)
		return
	}
	found := false
	err := app.sessions.Iterate(r.Context(), func(ctx context.Context) error {
		if app.sessions.GetInt(ctx, authenticatedUserIDSessionKey) == user.ID && app.sessions.GetString(ctx, accountSessionIDKey) == targetID {
			found = true
			return app.sessions.Destroy(ctx)
		}
		return nil
	})
	if err != nil {
		app.serverErrorResponse(w, r, err)
		return
	}
	if !found {
		app.notFoundResponse(w, r)
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

func (app *application) updateAccountProfileHandler(w http.ResponseWriter, r *http.Request) {
	user, _ := app.contextGetAuthenticatedUser(r)
	var input struct {
		Name  string `json:"name"`
		Color string `json:"color"`
	}
	if err := app.readJSON(w, r, &input); err != nil {
		app.badRequestResponse(w, r, err)
		return
	}
	user.Name = strings.TrimSpace(input.Name)
	if color := strings.TrimSpace(input.Color); color != "" {
		user.Color = color
	}
	v := validate.New()
	storage.ValidateUser(v, user)
	if !v.Valid() {
		app.failedValidationResponse(w, r, v.Errors)
		return
	}
	updated, err := app.models.Users.Update(user)
	if err != nil {
		app.respondToAccountError(w, r, err)
		return
	}
	if err = app.writeJSON(w, http.StatusOK, envelope{"user": updated}, nil); err != nil {
		app.serverErrorResponse(w, r, err)
	}
}

func (app *application) updateAccountPasswordHandler(w http.ResponseWriter, r *http.Request) {
	user, _ := app.contextGetAuthenticatedUser(r)
	var input struct {
		CurrentPassword string `json:"current_password"`
		NewPassword     string `json:"new_password"`
	}
	if err := app.readJSON(w, r, &input); err != nil {
		app.badRequestResponse(w, r, err)
		return
	}
	v := validate.New()
	auth.ValidatePasswordPlaintext(v, input.CurrentPassword)
	auth.ValidatePasswordPlaintext(v, input.NewPassword)
	if !v.Valid() {
		app.failedValidationResponse(w, r, v.Errors)
		return
	}
	match, err := user.Password.Matches(input.CurrentPassword)
	if err != nil {
		app.serverErrorResponse(w, r, err)
		return
	}
	if !match {
		app.invalidCredentialsResponse(w, r)
		return
	}
	if err = user.Password.Set(input.NewPassword); err != nil {
		app.serverErrorResponse(w, r, err)
		return
	}
	if _, err = app.models.Users.Update(user); err != nil {
		app.respondToAccountError(w, r, err)
		return
	}
	if err = app.models.Tokens.DeleteAllForUser(auth.ScopeAuthentication, user.ID); err != nil {
		app.serverErrorResponse(w, r, err)
		return
	}
	if err = app.models.Tokens.DeleteAllForUser(auth.ScopePasswordReset, user.ID); err != nil {
		app.serverErrorResponse(w, r, err)
		return
	}
	if err = app.writeJSON(w, http.StatusOK, envelope{"message": "password updated"}, nil); err != nil {
		app.serverErrorResponse(w, r, err)
	}
}

func (app *application) requestAccountEmailChangeHandler(w http.ResponseWriter, r *http.Request) {
	user, _ := app.contextGetAuthenticatedUser(r)
	var input struct {
		Email           string `json:"email"`
		CurrentPassword string `json:"current_password"`
	}
	if err := app.readJSON(w, r, &input); err != nil {
		app.badRequestResponse(w, r, err)
		return
	}
	input.Email = strings.ToLower(strings.TrimSpace(input.Email))
	v := validate.New()
	storage.ValidateEmail(v, input.Email)
	auth.ValidatePasswordPlaintext(v, input.CurrentPassword)
	if !v.Valid() {
		app.failedValidationResponse(w, r, v.Errors)
		return
	}
	match, err := user.Password.Matches(input.CurrentPassword)
	if err != nil {
		app.serverErrorResponse(w, r, err)
		return
	}
	if !match {
		app.invalidCredentialsResponse(w, r)
		return
	}
	if existing, lookupErr := app.models.Users.GetByEmail(input.Email); lookupErr == nil && existing.ID != user.ID {
		v.AddError("email", "email address is already registered")
		app.failedValidationResponse(w, r, v.Errors)
		return
	} else if lookupErr != nil && !errors.Is(lookupErr, storage.ErrRecordNotFound) {
		app.serverErrorResponse(w, r, lookupErr)
		return
	}
	token, err := app.models.Users.CreateEmailChange(user.ID, input.Email, 45*time.Minute)
	if err != nil {
		app.respondToAccountError(w, r, err)
		return
	}
	app.background(func() {
		data := map[string]any{"confirmationURL": strings.TrimRight(app.config.WebBaseURL, "/") + "/account/email-confirm?token=" + token}
		if sendErr := app.mailer.Send(input.Email, "email_change.tmpl", data); sendErr != nil {
			app.logger.Error(sendErr.Error())
		}
	})
	if err = app.writeJSON(w, http.StatusAccepted, envelope{"message": "confirmation email sent"}, nil); err != nil {
		app.serverErrorResponse(w, r, err)
	}
}

func (app *application) confirmAccountEmailHandler(w http.ResponseWriter, r *http.Request) {
	user, _ := app.contextGetAuthenticatedUser(r)
	var input struct {
		Token string `json:"token"`
	}
	if err := app.readJSON(w, r, &input); err != nil {
		app.badRequestResponse(w, r, err)
		return
	}
	v := validate.New()
	auth.ValidateTokenPlaintext(v, input.Token)
	if !v.Valid() {
		app.failedValidationResponse(w, r, v.Errors)
		return
	}
	updated, err := app.models.Users.ConfirmEmailChange(input.Token, user.ID)
	if err != nil {
		app.respondToAccountError(w, r, err)
		return
	}
	if err = app.models.Tokens.DeleteAllForUser(auth.ScopeAuthentication, user.ID); err != nil {
		app.serverErrorResponse(w, r, err)
		return
	}
	if err = app.writeJSON(w, http.StatusOK, envelope{"user": updated}, nil); err != nil {
		app.serverErrorResponse(w, r, err)
	}
}

func (app *application) respondToAccountError(w http.ResponseWriter, r *http.Request, err error) {
	switch {
	case errors.Is(err, storage.ErrDuplicateEmail):
		app.failedValidationResponse(w, r, map[string]string{"email": "email address is already registered"})
	case errors.Is(err, storage.ErrRecordNotFound):
		app.notFoundResponse(w, r)
	case errors.Is(err, storage.ErrEditConflict):
		app.editConflictResponse(w, r)
	default:
		app.serverErrorResponse(w, r, err)
	}
}