package command

import (
	"fmt"
	"path/filepath"

	"github.com/hashicorp/terraform/configs"
	"github.com/hashicorp/terraform/internal/getproviders"
	"github.com/hashicorp/terraform/tfdiags"
	"github.com/xlab/treeprint"
)

// ProvidersCommand is a Command implementation that prints out information
// about the providers used in the current configuration/state.
type ProvidersCommand struct {
	Meta
}

func (c *ProvidersCommand) Help() string {
	return providersCommandHelp
}

func (c *ProvidersCommand) Synopsis() string {
	return "Prints a tree of the providers used in the configuration"
}

func (c *ProvidersCommand) Run(args []string) int {
	args = c.Meta.process(args)
	cmdFlags := c.Meta.defaultFlagSet("providers")
	cmdFlags.Usage = func() { c.Ui.Error(c.Help()) }
	if err := cmdFlags.Parse(args); err != nil {
		c.Ui.Error(fmt.Sprintf("Error parsing command-line flags: %s\n", err.Error()))
		return 1
	}

	configPath, err := ModulePath(cmdFlags.Args())
	if err != nil {
		c.Ui.Error(err.Error())
		return 1
	}

	var diags tfdiags.Diagnostics

	empty, err := configs.IsEmptyDir(configPath)
	if err != nil {
		diags = diags.Append(tfdiags.Sourceless(
			tfdiags.Error,
			"Error validating configuration directory",
			fmt.Sprintf("Terraform encountered an unexpected error while verifying that the given configuration directory is valid: %s.", err),
		))
		c.showDiagnostics(diags)
		return 1
	}
	if empty {
		absPath, err := filepath.Abs(configPath)
		if err != nil {
			absPath = configPath
		}
		diags = diags.Append(tfdiags.Sourceless(
			tfdiags.Error,
			"No configuration files",
			fmt.Sprintf("The directory %s contains no Terraform configuration files.", absPath),
		))
		c.showDiagnostics(diags)
		return 1
	}

	config, configDiags := c.loadConfig(configPath)
	diags = diags.Append(configDiags)
	if configDiags.HasErrors() {
		c.showDiagnostics(diags)
		return 1
	}

	// Load the backend
	b, backendDiags := c.Backend(&BackendOpts{
		Config: config.Module.Backend,
	})
	diags = diags.Append(backendDiags)
	if backendDiags.HasErrors() {
		c.showDiagnostics(diags)
		return 1
	}

	// Get the state
	env := c.Workspace()
	s, err := b.StateMgr(env)
	if err != nil {
		c.Ui.Error(fmt.Sprintf("Failed to load state: %s", err))
		return 1
	}
	if err := s.RefreshState(); err != nil {
		c.Ui.Error(fmt.Sprintf("Failed to load state: %s", err))
		return 1
	}

	reqs, reqDiags := config.ProviderRequirements()
	if reqDiags.HasErrors() {
		c.showDiagnostics(configDiags)
		return 1
	}

	state := s.State()
	if state != nil {
		stateReqs := state.ProviderRequirements()
		reqs = reqs.Merge(stateReqs)
	}

	printRoot := treeprint.New()
	providersCommandPopulateTreeNode(printRoot, reqs)

	c.Ui.Output(printRoot.String())

	c.showDiagnostics(diags)
	if diags.HasErrors() {
		return 1
	}
	return 0
}

func providersCommandPopulateTreeNode(node treeprint.Tree, deps getproviders.Requirements) {
	for fqn, dep := range deps {
		versionsStr := getproviders.VersionConstraintsString(dep)
		if versionsStr != "" {
			versionsStr = " " + versionsStr
		}
		node.AddNode(fmt.Sprintf("provider[%s]%s", fqn.String(), versionsStr))
	}
}

const providersCommandHelp = `
Usage: terraform providers [dir]

  Prints out a list of providers required by the configuration and state.

  This provides an overview of all of the provider requirements as an aid to
  understanding why particular provider plugins are needed and why particular
  versions are selected.
`