generate.go

package run // import "github.com/episub/gnorm/run"

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"text/template"
	"time"

	"github.com/pkg/errors"

	"github.com/episub/gnorm/environ"
	"github.com/episub/gnorm/run/data"
)

// Generate reads your database, gets the schema for it, and then generates
// files based on your templates and your configuration.
func Generate(env environ.Values, cfg *Config) error {
	info, err := cfg.Driver.Parse(env.Log, cfg.ConnStr, cfg.Schemas, makeFilter(cfg.IncludeTables, cfg.ExcludeTables))
	if err != nil {
		return err
	}
	db, err := makeData(env.Log, info, cfg)
	if err != nil {
		return err
	}
	if len(cfg.SchemaPaths) == 0 {
		env.Log.Println("No SchemaPaths specified, skipping schemas.")
	} else {
		if err := generateSchemas(env, cfg, db); err != nil {
			return err
		}
	}
	if len(cfg.EnumPaths) == 0 {
		env.Log.Println("No EnumPath specified, skipping enums.")
	} else {
		if err := generateEnums(env, cfg, db); err != nil {
			return err
		}
	}
	if len(cfg.TablePaths) == 0 {
		env.Log.Println("No table path specified, skipping tables.")
	} else {
		if err := generateTables(env, cfg, db); err != nil {
			return err
		}
	}
	return copyStaticFiles(env, cfg.StaticDir, cfg.OutputDir)
}

func generateSchemas(env environ.Values, cfg *Config, db *data.DBData) error {
	for _, schema := range db.Schemas {
		fileData := struct{ Schema string }{Schema: schema.Name}
		contents := data.SchemaData{
			Schema: schema,
			DB:     db,
			Config: cfg.ConfigData,
			Params: cfg.Params,
		}
		for _, target := range cfg.SchemaPaths {
			env.Log.Printf("Generating output for schema %v", schema.Name)
			if err := genFile(env, fileData, contents, target, cfg.NoOverwriteGlobs, cfg.PostRun, cfg.OutputDir, cfg.TemplateEngine); err != nil {
				return errors.WithMessage(err, "generating file for schema "+schema.Name)
			}
		}
	}
	return nil
}

type templateEngine struct {
	CommandLine []*template.Template
	UseStdin    bool
	UseStdout   bool
}

func generateEnums(env environ.Values, cfg *Config, db *data.DBData) error {
	for _, schema := range db.Schemas {
		for _, enum := range schema.Enums {
			fileData := struct{ Schema, Enum, Table string }{Schema: schema.Name, Enum: enum.Name, Table: enum.Table.DBName}
			contents := data.EnumData{
				Enum:   enum,
				DB:     db,
				Config: cfg.ConfigData,
				Params: cfg.Params,
			}
			for _, target := range cfg.EnumPaths {
				if err := genFile(env, fileData, contents, target, cfg.NoOverwriteGlobs, cfg.PostRun, cfg.OutputDir, cfg.TemplateEngine); err != nil {
					env.Log.Printf("Generating output for enum %v", enum.Name)
					return errors.WithMessage(err, "generating file for enum "+enum.Name)
				}
			}
		}
	}
	return nil
}

func generateTables(env environ.Values, cfg *Config, db *data.DBData) error {
	for _, schema := range db.Schemas {
		for _, table := range schema.Tables {
			contents := data.TableData{
				Table:  table,
				DB:     db,
				Config: cfg.ConfigData,
				Params: cfg.Params,
			}
			fileData := struct{ Schema, Table string }{Schema: schema.Name, Table: table.Name}
			for _, target := range cfg.TablePaths {
				if err := genFile(env, fileData, contents, target, cfg.NoOverwriteGlobs, cfg.PostRun, cfg.OutputDir, cfg.TemplateEngine); err != nil {
					env.Log.Printf("Generating output for table %v", table.Name)
					return errors.WithMessage(err, "generating file for table "+table.Name)
				}
			}
		}
	}
	return nil
}

func genFile(env environ.Values, filedata, contents interface{}, target OutputTarget, noOverwriteGlobs, postrun []string, outputDir string, engine templateEngine) error {
	buf := &bytes.Buffer{}
	err := target.Filename.Execute(buf, filedata)
	if err != nil {
		return errors.WithMessage(err, "failed to run Filename template")
	}
	outputPath := filepath.Join(outputDir, buf.String())

	// if file exists and filename matches glob, abort
	if _, err := os.Stat(outputPath); err == nil {
		for _, glob := range noOverwriteGlobs {
			m, err := filepath.Match(glob, buf.String())
			if err != nil {
				return errors.WithMessage(err, "error checking glob")
			}
			if m {
				env.Log.Printf("Skipping generation for file %s", buf.String())
				return nil
			}
		}
	}

	if err := os.MkdirAll(filepath.Dir(outputPath), 0700); err != nil {
		return errors.WithMessage(err, "error creating template output directory")
	}

	if len(engine.CommandLine) != 0 {
		if err := runExternalEngine(env.Env, outputPath, target.ContentsPath, contents, engine); err != nil {
			return err
		}
	} else {
		outbuf := &bytes.Buffer{}
		if err := target.Contents.Execute(outbuf, contents); err != nil {
			return errors.WithMessage(err, "failed to run contents template")
		}
		if err := ioutil.WriteFile(outputPath, outbuf.Bytes(), 0600); err != nil {
			return errors.Wrapf(err, "error writing generated file %q", outputPath)
		}
	}
	if len(postrun) > 0 {
		return doPostRun(env, outputPath, postrun)
	}
	return nil
}

func runExternalEngine(env map[string]string, outputPath, templatePath string, contents interface{}, engine templateEngine) error {
	b, err := json.Marshal(contents)
	if err != nil {
		return errors.WithMessage(err, "can't render data for template to json")
	}
	var jsonDataFile string
	if !engine.UseStdin {
		f, err := ioutil.TempFile("", "*.json")
		if err != nil {
			return errors.WithMessage(err, "can't create temp file with json")
		}
		defer f.Close()
		jsonDataFile = f.Name()
		if _, err = f.Write(b); err != nil {
			return errors.WithMessage(err, "failed to write json to file "+jsonDataFile)
		}
		f.Close()
		defer os.Remove(jsonDataFile)
	}
	data := map[string]string{
		"Data":     jsonDataFile,
		"Output":   outputPath,
		"Template": templatePath,
	}
	var args []string
	for _, t := range engine.CommandLine {
		var buf bytes.Buffer
		if err := t.Execute(&buf, data); err != nil {
			return errors.WithMessage(err, "failed to run fill template engine command line variables")
		}
		args = append(args, buf.String())
	}
	cmd := exec.Command(args[0], args[1:]...)
	if engine.UseStdin {
		cmd.Stdin = bytes.NewReader(b)
	}
	var stderr bytes.Buffer
	var stdout bytes.Buffer
	cmd.Stderr = &stderr
	if engine.UseStdout {
		cmd.Stdout = &stdout
	}
	envvars := make([]string, 0, len(env))
	for k, v := range env {
		envvars = append(envvars, k+"="+v)
	}
	cmd.Env = envvars
	if err := cmd.Run(); err != nil {
		cl := strings.Join(args, " ")
		if stderr.Len() > 0 {
			return errors.WithMessage(err, fmt.Sprintf("failed to run template engine command line %q\n%s", cl, stderr.String()))
		}
		return errors.WithMessage(err, "failed to run template engine command line: "+cl)
	}
	if engine.UseStdout {
		if err := ioutil.WriteFile(outputPath, stdout.Bytes(), 0600); err != nil {
			return errors.WithMessage(err, "failed to write output file "+outputPath)
		}
	}
	return nil
}

func doPostRun(env environ.Values, file string, postrun []string) error {
	newenv := make(map[string]string, len(env.Env)+1)
	for k := range env.Env {
		newenv[k] = env.Env[k]
	}
	run := make([]string, len(postrun))
	newenv["GNORMFILE"] = file
	conv := func(s string) string { return newenv[s] }
	for x, s := range postrun {
		run[x] = os.Expand(s, conv)
	}
	var cmd *exec.Cmd
	ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
	defer cancel()
	if len(run) > 1 {
		cmd = exec.CommandContext(ctx, run[0], run[1:]...)
	} else {
		cmd = exec.CommandContext(ctx, run[0])
	}
	cmd.Stderr = env.Stderr
	cmd.Stdout = env.Stdout
	if err := cmd.Run(); err != nil {
		return errors.Wrapf(err, "error running postrun command %q", run)
	}
	return nil
}

// copyStaticFiles copies files recursively from src directory to dest directory
// while preserving the directory structure
func copyStaticFiles(env environ.Values, src string, dest string) error {
	if src == "" || dest == "" {
		return nil
	}
	stat, err := os.Stat(src)
	if err != nil {
		return err
	}
	if !stat.IsDir() {
		return fmt.Errorf("Outputdir specifies a directory path that already exists as file %s", dest)
	}
	var dstat os.FileInfo
	dstat, err = os.Stat(dest)
	if err != nil {
		if os.IsNotExist(err) {
			err = os.MkdirAll(dest, stat.Mode())
			if err != nil {
				return err
			}
			dstat = stat
		} else {
			return err
		}
	}
	if !dstat.IsDir() {
		return fmt.Errorf("%s is not a directory", dest)
	}
	return filepath.Walk(src, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if info.IsDir() {
			return nil
		}
		base := filepath.Dir(path)
		rel, err := filepath.Rel(src, base)
		if err != nil {
			return err
		}
		o := filepath.Join(dest, rel)
		err = os.MkdirAll(o, stat.Mode())
		if err != nil {
			return err
		}
		f, err := os.Open(path)
		if err != nil {
			return err
		}
		defer f.Close()

		t, err := os.OpenFile(filepath.Join(o, filepath.Base(path)), os.O_RDWR|os.O_TRUNC|os.O_CREATE, info.Mode())
		if err != nil {
			return err
		}
		defer t.Close()
		_, err = io.Copy(t, f)
		return err
	})
}