package events

import (
	"fmt"
	"os"
	"path/filepath"

	"github.com/pkg/errors"
	"github.com/runatlantis/atlantis/server/events/locking"
	"github.com/runatlantis/atlantis/server/events/models"
	"github.com/runatlantis/atlantis/server/events/run"
	"github.com/runatlantis/atlantis/server/events/terraform"
	"github.com/runatlantis/atlantis/server/events/vcs"
)

//go:generate pegomock generate -m --use-experimental-model-gen --package mocks -o mocks/mock_lock_url_generator.go LockURLGenerator

// LockURLGenerator consumes lock URLs.
type LockURLGenerator interface {
	// SetLockURL takes a function that given a lock id, will return a url
	// to view that lock.
	SetLockURL(func(id string) (url string))
}

// atlantisUserTFVar is the name of the variable we execute terraform
// with, containing the vcs username of who is running the command
const atlantisUserTFVar = "atlantis_user"

// PlanExecutor handles everything related to running terraform plan.
type PlanExecutor struct {
	VCSClient         vcs.ClientProxy
	Terraform         terraform.Client
	Locker            locking.Locker
	LockURL           func(id string) (url string)
	Run               run.Runner
	Workspace         AtlantisWorkspace
	ProjectPreExecute ProjectPreExecutor
	ProjectFinder     ProjectFinder
}

// PlanSuccess is the result of a successful plan.
type PlanSuccess struct {
	TerraformOutput string
	LockURL         string
}

// SetLockURL takes a function that given a lock id, will return a url
// to view that lock.
func (p *PlanExecutor) SetLockURL(f func(id string) (url string)) {
	p.LockURL = f
}

// Execute executes terraform plan for the ctx.
func (p *PlanExecutor) Execute(ctx *CommandContext) CommandResponse {
	cloneDir, err := p.Workspace.Clone(ctx.Log, ctx.BaseRepo, ctx.HeadRepo, ctx.Pull, ctx.Command.Workspace)
	if err != nil {
		return CommandResponse{Error: err}
	}

	var projects []models.Project
	if ctx.Command.Dir == "" {
		// If they didn't specify a directory to plan in, figure out what
		// projects have been modified so we know where to run plan.
		modifiedFiles, err := p.VCSClient.GetModifiedFiles(ctx.BaseRepo, ctx.Pull, ctx.VCSHost)
		if err != nil {
			return CommandResponse{Error: errors.Wrap(err, "getting modified files")}
		}
		ctx.Log.Info("found %d files modified in this pull request", len(modifiedFiles))
		projects = p.ProjectFinder.DetermineProjects(ctx.Log, modifiedFiles, ctx.BaseRepo.FullName, cloneDir)
		if len(projects) == 0 {
			return CommandResponse{Failure: "No Terraform files were modified."}
		}
	} else {
		projects = []models.Project{{
			Path:         ctx.Command.Dir,
			RepoFullName: ctx.BaseRepo.FullName,
		}}
	}

	var results []ProjectResult
	for _, project := range projects {
		ctx.Log.Info("running plan for project at path %q", project.Path)
		result := p.plan(ctx, cloneDir, project)
		result.Path = project.Path
		results = append(results, result)
	}
	return CommandResponse{ProjectResults: results}
}

func (p *PlanExecutor) plan(ctx *CommandContext, repoDir string, project models.Project) ProjectResult {
	preExecute := p.ProjectPreExecute.Execute(ctx, repoDir, project)
	if preExecute.ProjectResult != (ProjectResult{}) {
		return preExecute.ProjectResult
	}
	config := preExecute.ProjectConfig
	terraformVersion := preExecute.TerraformVersion
	workspace := ctx.Command.Workspace

	// Run terraform plan.
	planFile := filepath.Join(repoDir, project.Path, fmt.Sprintf("%s.tfplan", workspace))
	userVar := fmt.Sprintf("%s=%s", atlantisUserTFVar, ctx.User.Username)
	planExtraArgs := config.GetExtraArguments(ctx.Command.Name.String())
	tfPlanCmd := append(append([]string{"plan", "-refresh", "-no-color", "-out", planFile, "-var", userVar}, planExtraArgs...), ctx.Command.Flags...)

	// Check if env/{workspace}.tfvars exist.
	envFileName := filepath.Join("env", workspace+".tfvars")
	if _, err := os.Stat(filepath.Join(repoDir, project.Path, envFileName)); err == nil {
		tfPlanCmd = append(tfPlanCmd, "-var-file", envFileName)
	}
	output, err := p.Terraform.RunCommandWithVersion(ctx.Log, filepath.Join(repoDir, project.Path), tfPlanCmd, terraformVersion, workspace)
	if err != nil {
		// Plan failed so unlock the state.
		if _, unlockErr := p.Locker.Unlock(preExecute.LockResponse.LockKey); unlockErr != nil {
			ctx.Log.Err("error unlocking state after plan error: %v", unlockErr)
		}
		return ProjectResult{Error: fmt.Errorf("%s\n%s", err.Error(), output)}
	}
	ctx.Log.Info("plan succeeded")

	// If there are post plan commands then run them.
	if len(config.PostPlan) > 0 {
		absolutePath := filepath.Join(repoDir, project.Path)
		_, err := p.Run.Execute(ctx.Log, config.PostPlan, absolutePath, workspace, terraformVersion, "post_plan")
		if err != nil {
			return ProjectResult{Error: errors.Wrap(err, "running post plan commands")}
		}
	}

	return ProjectResult{
		PlanSuccess: &PlanSuccess{
			TerraformOutput: output,
			LockURL:         p.LockURL(preExecute.LockResponse.LockKey),
		},
	}
}