package local

import (
	"context"
	"fmt"
	"log"

	"github.com/hashicorp/errwrap"
	"github.com/hashicorp/go-multierror"
	"github.com/hashicorp/terraform/backend"
	"github.com/hashicorp/terraform/state"
	"github.com/hashicorp/terraform/terraform"
)

func (b *Local) opApply(
	ctx context.Context,
	op *backend.Operation,
	runningOp *backend.RunningOperation) {
	log.Printf("[INFO] backend/local: starting Apply operation")

	// Setup our count hook that keeps track of resource changes
	countHook := new(CountHook)
	stateHook := new(StateHook)
	if b.ContextOpts == nil {
		b.ContextOpts = new(terraform.ContextOpts)
	}
	old := b.ContextOpts.Hooks
	defer func() { b.ContextOpts.Hooks = old }()
	b.ContextOpts.Hooks = append(b.ContextOpts.Hooks, countHook, stateHook)

	// Get our context
	tfCtx, opState, err := b.context(op)
	if err != nil {
		runningOp.Err = err
		return
	}

	// context acquired the state, and therefor the lock.
	// Unlock it when the operation is complete
	defer func() {
		if s, ok := opState.(state.Locker); op.LockState && ok {
			if err := s.Unlock(); err != nil {
				runningOp.Err = multierror.Append(runningOp.Err,
					errwrap.Wrapf("Error unlocking state:\n\n"+
						"{{err}}\n\n"+
						"The Terraform operation completed but there was an error unlocking the state.\n"+
						"This may require unlocking the state manually with the `terraform unlock` command\n",
						err,
					),
				)
			}
		}
	}()

	// Setup the state
	runningOp.State = tfCtx.State()

	// If we weren't given a plan, then we refresh/plan
	if op.Plan == nil {
		// If we're refreshing before apply, perform that
		if op.PlanRefresh {
			log.Printf("[INFO] backend/local: apply calling Refresh")
			_, err := tfCtx.Refresh()
			if err != nil {
				runningOp.Err = errwrap.Wrapf("Error refreshing state: {{err}}", err)
				return
			}
		}

		// Perform the plan
		log.Printf("[INFO] backend/local: apply calling Plan")
		if _, err := tfCtx.Plan(); err != nil {
			runningOp.Err = errwrap.Wrapf("Error running plan: {{err}}", err)
			return
		}
	}

	// Setup our hook for continuous state updates
	stateHook.State = opState

	// Start the apply in a goroutine so that we can be interrupted.
	var applyState *terraform.State
	var applyErr error
	doneCh := make(chan struct{})
	go func() {
		defer close(doneCh)
		applyState, applyErr = tfCtx.Apply()

		/*
			// Record any shadow errors for later
			if err := ctx.ShadowError(); err != nil {
				shadowErr = multierror.Append(shadowErr, multierror.Prefix(
					err, "apply operation:"))
			}
		*/
	}()

	// Wait for the apply to finish or for us to be interrupted so
	// we can handle it properly.
	err = nil
	select {
	case <-ctx.Done():
		if b.CLI != nil {
			b.CLI.Output("Interrupt received. Gracefully shutting down...")
		}

		// Stop execution
		go tfCtx.Stop()

		// Wait for completion still
		<-doneCh
	case <-doneCh:
	}

	// Store the final state
	runningOp.State = applyState

	// Persist the state
	if err := opState.WriteState(applyState); err != nil {
		runningOp.Err = fmt.Errorf("Failed to save state: %s", err)
		return
	}
	if err := opState.PersistState(); err != nil {
		runningOp.Err = fmt.Errorf("Failed to save state: %s", err)
		return
	}

	if applyErr != nil {
		runningOp.Err = fmt.Errorf(
			"Error applying plan:\n\n"+
				"%s\n\n"+
				"Terraform does not automatically rollback in the face of errors.\n"+
				"Instead, your Terraform state file has been partially updated with\n"+
				"any resources that successfully completed. Please address the error\n"+
				"above and apply again to incrementally change your infrastructure.",
			multierror.Flatten(applyErr))
		return
	}

	// If we have a UI, output the results
	if b.CLI != nil {
		if op.Destroy {
			b.CLI.Output(b.Colorize().Color(fmt.Sprintf(
				"[reset][bold][green]\n"+
					"Destroy complete! Resources: %d destroyed.",
				countHook.Removed)))
		} else {
			b.CLI.Output(b.Colorize().Color(fmt.Sprintf(
				"[reset][bold][green]\n"+
					"Apply complete! Resources: %d added, %d changed, %d destroyed.",
				countHook.Added,
				countHook.Changed,
				countHook.Removed)))
		}

		if countHook.Added > 0 || countHook.Changed > 0 {
			b.CLI.Output(b.Colorize().Color(fmt.Sprintf(
				"[reset]\n"+
					"The state of your infrastructure has been saved to the path\n"+
					"below. This state is required to modify and destroy your\n"+
					"infrastructure, so keep it safe. To inspect the complete state\n"+
					"use the `terraform show` command.\n\n"+
					"State path: %s",
				b.StateOutPath)))
		}
	}
}