// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0

package provider

import (
	"context"
	"math"

	"github.com/hashicorp/terraform-plugin-framework/function"
)

var (
	_ function.Function = &ComputeTaxFunction{}
)

type ComputeTaxFunction struct{}

func NewComputeTaxFunction() function.Function {
	return &ComputeTaxFunction{}
}

func (f *ComputeTaxFunction) Metadata(ctx context.Context, req function.MetadataRequest, resp *function.MetadataResponse) {
	resp.Name = "compute_tax"
}

func (f *ComputeTaxFunction) Definition(ctx context.Context, req function.DefinitionRequest, resp *function.DefinitionResponse) {
	resp.Definition = function.Definition{
		Parameters: []function.Parameter{
			function.Float64Parameter{
				Description: "Price of coffee item.",
				Name:        "price",
			},
			function.Float64Parameter{
				Description: "Tax rate. 0.085 == 8.5%",
				Name:        "rate",
			},
		},
		Return:      function.Float64Return{},
		Summary:     "Compute tax for coffee",
		Description: "Given a price and tax rate, return the total cost including tax.",
	}
}

func (f *ComputeTaxFunction) Run(ctx context.Context, req function.RunRequest, resp *function.RunResponse) {
	var (
		price, rate, total float64
	)

	// 1. Read Terraform argument data into the variables.
	resp.Error = function.ConcatFuncErrors(
		resp.Error,
		req.Arguments.Get(ctx, &price, &rate),
	)

	// 2. Perform the calculation
	total = math.Round((price+price*rate)*100) / 100

	// 3. Set the result on the state
	resp.Error = function.ConcatFuncErrors(
		resp.Error,
		resp.Result.Set(ctx, total),
	)
}