package remote

import (
	"context"
	"log"
	"strings"

	"github.com/hashicorp/errwrap"
	tfe "github.com/hashicorp/go-tfe"
	"github.com/hashicorp/terraform/backend"
	"github.com/hashicorp/terraform/command/clistate"
	"github.com/hashicorp/terraform/states/statemgr"
	"github.com/hashicorp/terraform/terraform"
	"github.com/hashicorp/terraform/tfdiags"
)

// Context implements backend.Enhanced.
func (b *Remote) Context(op *backend.Operation) (*terraform.Context, statemgr.Full, tfdiags.Diagnostics) {
	var diags tfdiags.Diagnostics

	if op.LockState {
		op.StateLocker = clistate.NewLocker(context.Background(), op.StateLockTimeout, b.CLI, b.cliColorize())
	} else {
		op.StateLocker = clistate.NewNoopLocker()
	}

	// Get the remote workspace name.
	workspace := op.Workspace
	switch {
	case op.Workspace == backend.DefaultStateName:
		workspace = b.workspace
	case b.prefix != "" && !strings.HasPrefix(op.Workspace, b.prefix):
		workspace = b.prefix + op.Workspace
	}

	// Get the latest state.
	log.Printf("[TRACE] backend/remote: requesting state manager for workspace %q", workspace)
	stateMgr, err := b.StateMgr(op.Workspace)
	if err != nil {
		diags = diags.Append(errwrap.Wrapf("Error loading state: {{err}}", err))
		return nil, nil, diags
	}

	log.Printf("[TRACE] backend/remote: requesting state lock for workspace %q", workspace)
	if err := op.StateLocker.Lock(stateMgr, op.Type.String()); err != nil {
		diags = diags.Append(errwrap.Wrapf("Error locking state: {{err}}", err))
		return nil, nil, diags
	}

	log.Printf("[TRACE] backend/remote: reading remote state for workspace %q", workspace)
	if err := stateMgr.RefreshState(); err != nil {
		diags = diags.Append(errwrap.Wrapf("Error loading state: {{err}}", err))
		return nil, nil, diags
	}

	// Initialize our context options
	var opts terraform.ContextOpts
	if v := b.ContextOpts; v != nil {
		opts = *v
	}

	// Copy set options from the operation
	opts.Destroy = op.Destroy
	opts.Targets = op.Targets
	opts.UIInput = op.UIIn

	// Load the latest state. If we enter contextFromPlanFile below then the
	// state snapshot in the plan file must match this, or else it'll return
	// error diagnostics.
	log.Printf("[TRACE] backend/remote: retrieving remote state snapshot for workspace %q", workspace)
	opts.State = stateMgr.State()

	log.Printf("[TRACE] backend/remote: loading configuration for the current working directory")
	config, configDiags := op.ConfigLoader.LoadConfig(op.ConfigDir)
	diags = diags.Append(configDiags)
	if configDiags.HasErrors() {
		return nil, nil, diags
	}
	opts.Config = config

	log.Printf("[TRACE] backend/remote: retrieving variables from workspace %q", workspace)
	tfeVariables, err := b.client.Variables.List(context.Background(), tfe.VariableListOptions{
		Organization: tfe.String(b.organization),
		Workspace:    tfe.String(workspace),
	})
	if err != nil && err != tfe.ErrResourceNotFound {
		diags = diags.Append(errwrap.Wrapf("Error loading variables: {{err}}", err))
		return nil, nil, diags
	}

	if tfeVariables != nil {
		for _, v := range tfeVariables.Items {
			if v.Sensitive {
				v.Value = "<sensitive>"
			}
			op.Variables[v.Key] = &unparsedVariableValue{
				value:  v.Value,
				source: terraform.ValueFromEnvVar,
			}
		}
	}

	variables, varDiags := backend.ParseVariableValues(op.Variables, config.Module.Variables)
	diags = diags.Append(varDiags)
	if diags.HasErrors() {
		return nil, nil, diags
	}
	if op.Variables != nil {
		opts.Variables = variables
	}

	tfCtx, ctxDiags := terraform.NewContext(&opts)
	diags = diags.Append(ctxDiags)

	log.Printf("[TRACE] backend/remote: finished building terraform.Context")

	return tfCtx, stateMgr, diags
}