package resource

import (
	"fmt"
	"log"
	"strings"

	"github.com/hashicorp/terraform/terraform"
)

// testStepConfig runs a config-mode test step
func testStepConfig(
	opts terraform.ContextOpts,
	state *terraform.State,
	step TestStep) (*terraform.State, error) {
	return testStep(opts, state, step)
}

func testStep(
	opts terraform.ContextOpts,
	state *terraform.State,
	step TestStep) (*terraform.State, error) {
	mod, err := testModule(opts, step)
	if err != nil {
		return state, err
	}

	// Build the context
	opts.Module = mod
	opts.State = state
	opts.Destroy = step.Destroy
	ctx, err := terraform.NewContext(&opts)
	if err != nil {
		return state, fmt.Errorf("Error initializing context: %s", err)
	}
	if ws, es := ctx.Validate(); len(ws) > 0 || len(es) > 0 {
		if len(es) > 0 {
			estrs := make([]string, len(es))
			for i, e := range es {
				estrs[i] = e.Error()
			}
			return state, fmt.Errorf(
				"Configuration is invalid.\n\nWarnings: %#v\n\nErrors: %#v",
				ws, estrs)
		}
		log.Printf("[WARN] Config warnings: %#v", ws)
	}

	// Refresh!
	state, err = ctx.Refresh()
	if err != nil {
		return state, fmt.Errorf(
			"Error refreshing: %s", err)
	}

	// Plan!
	if p, err := ctx.Plan(); err != nil {
		return state, fmt.Errorf(
			"Error planning: %s", err)
	} else {
		log.Printf("[WARN] Test: Step plan: %s", p)
	}

	// We need to keep a copy of the state prior to destroying
	// such that destroy steps can verify their behaviour in the check
	// function
	stateBeforeApplication := state.DeepCopy()

	// Apply!
	state, err = ctx.Apply()
	if err != nil {
		return state, fmt.Errorf("Error applying: %s", err)
	}

	// Check! Excitement!
	if step.Check != nil {
		if step.Destroy {
			if err := step.Check(stateBeforeApplication); err != nil {
				return state, fmt.Errorf("Check failed: %s", err)
			}
		} else {
			if err := step.Check(state); err != nil {
				return state, fmt.Errorf("Check failed: %s", err)
			}
		}
	}

	// Now, verify that Plan is now empty and we don't have a perpetual diff issue
	// We do this with TWO plans. One without a refresh.
	var p *terraform.Plan
	if p, err = ctx.Plan(); err != nil {
		return state, fmt.Errorf("Error on follow-up plan: %s", err)
	}
	if p.Diff != nil && !p.Diff.Empty() {
		if step.ExpectNonEmptyPlan {
			log.Printf("[INFO] Got non-empty plan, as expected:\n\n%s", p)
		} else {
			return state, fmt.Errorf(
				"After applying this step, the plan was not empty:\n\n%s", p)
		}
	}

	// And another after a Refresh.
	if !step.Destroy || (step.Destroy && !step.PreventPostDestroyRefresh) {
		state, err = ctx.Refresh()
		if err != nil {
			return state, fmt.Errorf(
				"Error on follow-up refresh: %s", err)
		}
	}
	if p, err = ctx.Plan(); err != nil {
		return state, fmt.Errorf("Error on second follow-up plan: %s", err)
	}
	empty := p.Diff == nil || p.Diff.Empty()

	// Data resources are tricky because they legitimately get instantiated
	// during refresh so that they will be already populated during the
	// plan walk. Because of this, if we have any data resources in the
	// config we'll end up wanting to destroy them again here. This is
	// acceptable and expected, and we'll treat it as "empty" for the
	// sake of this testing.
	if step.Destroy {
		empty = true

		for _, moduleDiff := range p.Diff.Modules {
			for k, instanceDiff := range moduleDiff.Resources {
				if !strings.HasPrefix(k, "data.") {
					empty = false
					break
				}

				if !instanceDiff.Destroy {
					empty = false
				}
			}
		}
	}

	if !empty {
		if step.ExpectNonEmptyPlan {
			log.Printf("[INFO] Got non-empty plan, as expected:\n\n%s", p)
		} else {
			return state, fmt.Errorf(
				"After applying this step and refreshing, "+
					"the plan was not empty:\n\n%s", p)
		}
	}

	// Made it here, but expected a non-empty plan, fail!
	if step.ExpectNonEmptyPlan && (p.Diff == nil || p.Diff.Empty()) {
		return state, fmt.Errorf("Expected a non-empty plan, but got an empty plan!")
	}

	// Made it here? Good job test step!
	return state, nil
}