package command

import (
	"encoding/json"
	"fmt"
	"strings"

	ctyjson "github.com/zclconf/go-cty/cty/json"

	"github.com/hashicorp/terraform/addrs"
	"github.com/hashicorp/terraform/repl"
	"github.com/hashicorp/terraform/states"
	"github.com/hashicorp/terraform/tfdiags"
)

// OutputCommand is a Command implementation that reads an output
// from a Terraform state and prints it.
type OutputCommand struct {
	Meta
}

func (c *OutputCommand) Run(args []string) int {
	args = c.Meta.process(args)
	var module, statePath string
	var jsonOutput bool
	cmdFlags := c.Meta.defaultFlagSet("output")
	cmdFlags.BoolVar(&jsonOutput, "json", false, "json")
	cmdFlags.StringVar(&statePath, "state", "", "path")
	cmdFlags.StringVar(&module, "module", "", "module")
	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
	}

	args = cmdFlags.Args()
	if len(args) > 1 {
		c.Ui.Error(
			"The output command expects exactly one argument with the name\n" +
				"of an output variable or no arguments to show all outputs.\n")
		cmdFlags.Usage()
		return 1
	}

	name := ""
	if len(args) > 0 {
		name = args[0]
	}

	if statePath != "" {
		c.Meta.statePath = statePath
	}

	var diags tfdiags.Diagnostics

	// Load the backend
	b, backendDiags := c.Backend(nil)
	diags = diags.Append(backendDiags)
	if backendDiags.HasErrors() {
		c.showDiagnostics(diags)
		return 1
	}

	env, err := c.Workspace()
	if err != nil {
		c.Ui.Error(fmt.Sprintf("Error selecting workspace: %s", err))
		return 1
	}

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

	if err := stateStore.RefreshState(); err != nil {
		c.Ui.Error(fmt.Sprintf("Failed to load state: %s", err))
		return 1
	}

	moduleAddr := addrs.RootModuleInstance
	if module != "" {
		// This option was supported prior to 0.12.0, but no longer supported
		// because we only persist the root module outputs in state.
		// (We could perhaps re-introduce this by doing an eval walk here to
		// repopulate them, similar to how "terraform console" does it, but
		// that requires more thought since it would imply this command
		// supporting remote operations, which is a big change.)
		diags = diags.Append(tfdiags.Sourceless(
			tfdiags.Error,
			"Unsupported option",
			"The -module option is no longer supported since Terraform 0.12, because now only root outputs are persisted in the state.",
		))
		c.showDiagnostics(diags)
		return 1
	}

	state := stateStore.State()
	if state == nil {
		state = states.NewState()
	}

	mod := state.Module(moduleAddr)
	if mod == nil {
		c.Ui.Error(fmt.Sprintf(
			"The module %s could not be found. There is nothing to output.",
			module))
		return 1
	}

	if !jsonOutput && (state.Empty() || len(mod.OutputValues) == 0) {
		diags = diags.Append(tfdiags.Sourceless(
			tfdiags.Warning,
			"No outputs found",
			"The state file either has no outputs defined, or all the defined "+
				"outputs are empty. Please define an output in your configuration "+
				"with the `output` keyword and run `terraform refresh` for it to "+
				"become available. If you are using interpolation, please verify "+
				"the interpolated value is not empty. You can use the "+
				"`terraform console` command to assist.",
		))
		c.showDiagnostics(diags)
		return 0
	}

	if name == "" {
		if jsonOutput {
			// Due to a historical accident, the switch from state version 2 to
			// 3 caused our JSON output here to be the full metadata about the
			// outputs rather than just the output values themselves as we'd
			// show in the single value case. We must now maintain that behavior
			// for compatibility, so this is an emulation of the JSON
			// serialization of outputs used in state format version 3.
			type OutputMeta struct {
				Sensitive bool            `json:"sensitive"`
				Type      json.RawMessage `json:"type"`
				Value     json.RawMessage `json:"value"`
			}
			outputs := map[string]OutputMeta{}

			for n, os := range mod.OutputValues {
				jsonVal, err := ctyjson.Marshal(os.Value, os.Value.Type())
				if err != nil {
					diags = diags.Append(err)
					c.showDiagnostics(diags)
					return 1
				}
				jsonType, err := ctyjson.MarshalType(os.Value.Type())
				if err != nil {
					diags = diags.Append(err)
					c.showDiagnostics(diags)
					return 1
				}
				outputs[n] = OutputMeta{
					Sensitive: os.Sensitive,
					Type:      json.RawMessage(jsonType),
					Value:     json.RawMessage(jsonVal),
				}
			}

			jsonOutputs, err := json.MarshalIndent(outputs, "", "  ")
			if err != nil {
				diags = diags.Append(err)
				c.showDiagnostics(diags)
				return 1
			}
			c.Ui.Output(string(jsonOutputs))
			return 0
		} else {
			c.Ui.Output(outputsAsString(state, moduleAddr, false))
			return 0
		}
	}

	os, ok := mod.OutputValues[name]
	if !ok {
		c.Ui.Error(fmt.Sprintf(
			"The output variable requested could not be found in the state\n" +
				"file. If you recently added this to your configuration, be\n" +
				"sure to run `terraform apply`, since the state won't be updated\n" +
				"with new output variables until that command is run."))
		return 1
	}
	v := os.Value

	if jsonOutput {
		jsonOutput, err := ctyjson.Marshal(v, v.Type())
		if err != nil {
			return 1
		}

		c.Ui.Output(string(jsonOutput))
	} else {
		result := repl.FormatValue(v, 0)
		c.Ui.Output(result)
	}

	return 0
}

func (c *OutputCommand) Help() string {
	helpText := `
Usage: terraform output [options] [NAME]

  Reads an output variable from a Terraform state file and prints
  the value. With no additional arguments, output will display all
  the outputs for the root module.  If NAME is not specified, all
  outputs are printed.

Options:

  -state=path      Path to the state file to read. Defaults to
                   "terraform.tfstate".

  -no-color        If specified, output won't contain any color.

  -json            If specified, machine readable output will be
                   printed in JSON format

`
	return strings.TrimSpace(helpText)
}

func (c *OutputCommand) Synopsis() string {
	return "Read an output from a state file"
}