package server

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

	version "github.com/hashicorp/go-version"
	"github.com/hootsuite/atlantis/aws"
	"github.com/hootsuite/atlantis/github"
	"github.com/hootsuite/atlantis/locking"
	"github.com/hootsuite/atlantis/models"
	"github.com/hootsuite/atlantis/prerun"
	"github.com/hootsuite/atlantis/terraform"
	"github.com/pkg/errors"
)

// PlanExecutor handles everything related to running the Terraform plan including integration with S3, Terraform, and GitHub
type PlanExecutor struct {
	github                *github.Client
	githubStatus          *GithubStatus
	awsConfig             *aws.Config
	s3Bucket              string
	terraform             *terraform.Client
	githubCommentRenderer *GithubCommentRenderer
	lockingClient         *locking.Client
	// LockURL is a function that given a lock id will return a url for lock view
	LockURL             func(id string) (url string)
	preRun              *prerun.PreRun
	configReader        *ConfigReader
	concurrentRunLocker *ConcurrentRunLocker
	workspace           *Workspace
}

/** Result Types **/
type PlanSuccess struct {
	TerraformOutput string
	LockURL         string
}

func (p *PlanExecutor) execute(ctx *CommandContext) {
	p.githubStatus.Update(ctx.BaseRepo, ctx.Pull, Pending, PlanStep)
	res := p.setupAndPlan(ctx)
	res.Command = Plan
	comment := p.githubCommentRenderer.render(res, ctx.Log.History.String(), ctx.Command.Verbose)
	p.github.CreateComment(ctx.BaseRepo, ctx.Pull, comment)
}

func (p *PlanExecutor) setupAndPlan(ctx *CommandContext) CommandResponse {
	if p.concurrentRunLocker.TryLock(ctx.BaseRepo.FullName, ctx.Command.Environment, ctx.Pull.Num) != true {
		return p.failureResponse(ctx,
			fmt.Sprintf("The %s environment is currently locked by another command that is running for this pull request. Wait until command is complete and try again.", ctx.Command.Environment))
	}
	defer p.concurrentRunLocker.Unlock(ctx.BaseRepo.FullName, ctx.Command.Environment, ctx.Pull.Num)

	// figure out what projects have been modified so we know where to run plan
	ctx.Log.Info("listing modified files from pull request")
	modifiedFiles, err := p.github.GetModifiedFiles(ctx.BaseRepo, ctx.Pull)
	if err != nil {
		return p.errorResponse(ctx, errors.Wrap(err, "getting modified files"))
	}
	modifiedTerraformFiles := p.filterToTerraform(modifiedFiles)
	if len(modifiedTerraformFiles) == 0 {
		return p.failureResponse(ctx, "No Terraform files were modified.")
	}
	ctx.Log.Debug("Found %d modified terraform files: %v", len(modifiedTerraformFiles), modifiedTerraformFiles)
	projects := p.ModifiedProjects(ctx.BaseRepo.FullName, modifiedTerraformFiles)

	cloneDir, err := p.workspace.Clone(ctx)
	if err != nil {
		return p.errorResponse(ctx, err)
	}

	results := []ProjectResult{}
	for _, project := range projects {
		result := p.plan(ctx, cloneDir, project)
		result.Path = project.Path
		results = append(results, result)
	}
	p.githubStatus.UpdatePathResult(ctx, results)
	return CommandResponse{ProjectResults: results}
}

// plan runs the steps necessary to run `terraform plan`. If there is an error, the error message will be encapsulated in error
// and the GeneratePlanResponse struct will also contain the full log including the error
func (p *PlanExecutor) plan(ctx *CommandContext, repoDir string, project models.Project) ProjectResult {
	ctx.Log.Info("generating plan at %q", project.Path)

	tfEnv := ctx.Command.Environment
	lockAttempt, err := p.lockingClient.TryLock(project, tfEnv, ctx.Pull, ctx.User)
	if err != nil {
		return ProjectResult{Error: errors.Wrap(err, "acquiring lock")}
	}
	if lockAttempt.LockAcquired == false && lockAttempt.CurrLock.Pull.Num != ctx.Pull.Num {
		return ProjectResult{Failure: fmt.Sprintf(
			"This project is currently locked by #%d. The locking plan must be applied or discarded before future plans can execute.",
			lockAttempt.CurrLock.Pull.Num)}
	}

	// check if config file is found, if not we continue the run
	var config ProjectConfig
	absolutePath := filepath.Join(repoDir, project.Path)
	var planExtraArgs []string
	if p.configReader.Exists(absolutePath) {
		config, err = p.configReader.Read(absolutePath)
		if err != nil {
			return ProjectResult{Error: err}
		}

		// add terraform arguments from project config
		planExtraArgs = config.GetExtraArguments(ctx.Command.Name.String())
	}

	// check if terraform version is >= 0.9.0
	terraformVersion := p.terraform.Version()
	if config.TerraformVersion != nil {
		terraformVersion = config.TerraformVersion
	}
	constraints, _ := version.NewConstraint(">= 0.9.0")
	if constraints.Check(terraformVersion) {
		// run terraform init and environment
		outputs, err := p.terraform.RunInitAndEnv(absolutePath, tfEnv, config.GetExtraArguments("init"))
		if err != nil {
			return ProjectResult{Error: err}
		}
		ctx.Log.Info("terraform init and environment commands ran successfully %s", outputs)
	} else {
		// run terraform get for 0.8.8 and below
		terraformGetCmd := append([]string{"get", "-no-color"}, config.GetExtraArguments("get")...)
		output, err := p.terraform.RunCommand(absolutePath, terraformGetCmd, nil)
		if err != nil {
			return ProjectResult{Error: err}
		}
		ctx.Log.Info("terraform get ran successfully %s", output)
	}

	// if there are pre plan commands then run them
	if len(config.PrePlan.Commands) > 0 {
		preRunOutput, err := p.preRun.Start(config.PrePlan.Commands, absolutePath, tfEnv, terraformVersion)
		if err != nil {
			return ProjectResult{Error: errors.Wrap(err, "running pre plan commands")}
		}
		ctx.Log.Info("Pre run output: \n%s", preRunOutput)
	}

	// set pull request creator as the session name
	p.awsConfig.SessionName = ctx.Pull.Author
	awsSession, err := p.awsConfig.CreateSession()
	if err != nil {
		ctx.Log.Err(err.Error())
		return ProjectResult{Error: err}
	}

	credVals, err := awsSession.Config.Credentials.Get()
	if err != nil {
		err = errors.Wrap(err, "getting assumed role credentials")
		ctx.Log.Err(err.Error())
		return ProjectResult{Error: err}
	}

	// Run terraform plan
	ctx.Log.Info("running terraform plan in directory %q", project.Path)
	planFile := filepath.Join(repoDir, project.Path, fmt.Sprintf("%s.tfplan", tfEnv))
	tfPlanCmd := []string{"plan", "-refresh", "-no-color", "-out", planFile}
	// append terraform arguments from config file
	tfPlanCmd = append(tfPlanCmd, planExtraArgs...)
	// check if env/{environment}.tfvars exist
	tfEnvFileName := filepath.Join("env", tfEnv+".tfvars")
	if _, err := os.Stat(filepath.Join(repoDir, project.Path, tfEnvFileName)); err == nil {
		tfPlanCmd = append(tfPlanCmd, "-var-file", tfEnvFileName)
	}
	output, err := p.terraform.RunCommand(filepath.Join(repoDir, project.Path), tfPlanCmd, []string{
		fmt.Sprintf("AWS_ACCESS_KEY_ID=%s", credVals.AccessKeyID),
		fmt.Sprintf("AWS_SECRET_ACCESS_KEY=%s", credVals.SecretAccessKey),
		fmt.Sprintf("AWS_SESSION_TOKEN=%s", credVals.SessionToken),
	})
	if err != nil {
		// plan failed so unlock the state
		if _, err := p.lockingClient.Unlock(lockAttempt.LockKey); err != nil {
			ctx.Log.Err("error unlocking state: %v", err)
		}
		return ProjectResult{Error: fmt.Errorf("%s\n%s", err.Error(), output)}
	}

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

func (p *PlanExecutor) filterToTerraform(files []string) []string {
	var out []string
	for _, fileName := range files {
		if !p.isInExcludeList(fileName) && strings.Contains(fileName, ".tf") {
			out = append(out, fileName)
		}
	}
	return out
}

func (p *PlanExecutor) isInExcludeList(fileName string) bool {
	return strings.Contains(fileName, "terraform.tfstate") || strings.Contains(fileName, "terraform.tfstate.backup") || strings.Contains(fileName, "_modules") || strings.Contains(fileName, "modules")
}

// ModifiedProjects returns the list of Terraform projects that have been changed due to the
// modified files
func (p *PlanExecutor) ModifiedProjects(repoFullName string, modifiedFiles []string) []models.Project {
	var projects []models.Project
	seenPaths := make(map[string]bool)
	for _, modifiedFile := range modifiedFiles {
		path := p.getProjectPath(modifiedFile)
		if _, ok := seenPaths[path]; !ok {
			projects = append(projects, models.NewProject(repoFullName, path))
			seenPaths[path] = true
		}
	}
	return projects
}

// getProjectPath returns the path to the project relative to the repo root
// if the project is at the root returns "."
func (p *PlanExecutor) getProjectPath(modifiedFilePath string) string {
	dir := path.Dir(modifiedFilePath)
	if path.Base(dir) == "env" {
		// if the modified file was inside an env/ directory, we treat this specially and
		// run plan one level up
		return path.Dir(dir)
	}
	return dir
}

func (p *PlanExecutor) failureResponse(ctx *CommandContext, msg string) CommandResponse {
	ctx.Log.Warn(msg)
	p.githubStatus.Update(ctx.BaseRepo, ctx.Pull, Failure, PlanStep)
	return CommandResponse{Failure: msg}
}

func (p *PlanExecutor) errorResponse(ctx *CommandContext, err error) CommandResponse {
	ctx.Log.Err(err.Error())
	p.githubStatus.Update(ctx.BaseRepo, ctx.Pull, Error, PlanStep)
	return CommandResponse{Error: err}
}