/*
gg is a recursive grep written in Go, with some shortcuts for everyday use.
*/
package main

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

	"github.com/bmatcuk/doublestar/v4"
	"github.com/spf13/cobra"
	"golang.org/x/sys/unix"
)

// TODO:
//  - it would be better to make fixed patterns case insensitive too.
//  - configurable defaults for exclude.

func main() {
	if err := rootCmd.Execute(); err != nil {
		os.Exit(1)
	}
}

var rootCmd = &cobra.Command{
	Use:   "gg pattern [path1 [path2 …]]",
	Short: "gg is a recursive grep",
	Long: `gg is a recursive grep. Given a regexp (or fixed pattern) it will search for
the pattern recursively in the current working directory. It will print a
coloured header per file along with the matching line and pattern.

It is possible to scan specific files or directories, rather than the default
current working directory. To do this, simply specify the path(s) as arguments
following the pattern.

It is possible to scan for multiple patterns using the -e (or -Q) argument,
which can be repeated multiple times. -e specifies a regular expression and
-Q a fixed pattern. When using either flag, any non-flag arguments are treated
as paths to scan.

Search defaults to case-sensitive but the -i flag may be passed to make regular
expression searches case-insensitive. Alternatively, the "(?i)" construct may be
added to a regular expression to make that specific expression case insensitive.
Fixed pattern matches are always case-sensitive.

Files and directories can be excluded with the -x option. This supports bash-style
globs with '*', '?', '[a-z]', '{this,that}', or '/**/' to match zero or more
directories. By default, .git and vim swap files are ignored.`,

	RunE: run,
}

var (
	searchRegexp []string
	regexps      []*regexp.Regexp
	searchFixed  []string
	searchBytes  [][]byte
	searchPath   []string
	excludeList  []string
	binaryFile   notPlainTextFlag
	minifiedFile notPlainTextFlag
	ignoreCase   bool
	noColour     bool
	display      *Display
	printedFull  bool
)

func init() {
	rootCmd.Flags().StringSliceVarP(&searchRegexp, "grep", "e", nil, "pattern to match (regular expression)")
	rootCmd.Flags().StringSliceVarP(&searchFixed, "fixed", "Q", nil, "pattern to match (fixed string)")
	rootCmd.Flags().StringSliceVarP(&excludeList, "exclude", "x", []string{".git", ".*.swp"}, "files/directories to exclude")
	rootCmd.Flags().BoolVarP(&ignoreCase, "ignore-case", "i", false, "make all searches case insensitive")
	rootCmd.Flags().BoolVarP(&noColour, "no-colour", "C", false, "disable colour output")
	rootCmd.Flags().Var(&binaryFile, "binary", "what to do with binary files")
	rootCmd.Flags().Var(&minifiedFile, "minified", "what to do with minified text files")
}

func run(c *cobra.Command, args []string) error {
	display = NewDisplay(noColour)

	if len(searchRegexp) == 0 && len(searchFixed) == 0 {
		if len(args) == 0 {
			return errors.New("no pattern specified")
		}
		searchRegexp = append(searchRegexp, args[0])
		args = args[1:]
	}

	searchPath = args
	if len(searchPath) == 0 {
		searchPath = append(searchPath, ".")
	}

	for i, x := range excludeList {
		if !strings.HasPrefix(x, "**/") && !strings.HasPrefix(x, "./") {
			x = "**/" + x
			excludeList[i] = x
		}
		if !doublestar.ValidatePattern(x) {
			return fmt.Errorf("invalid exclude pattern %q", x)
		}
	}

	for _, r := range searchRegexp {
		if ignoreCase {
			r = "(?i)" + r
		}
		re, err := regexp.Compile(r)
		if err != nil {
			return err
		}
		regexps = append(regexps, re)
	}

	for _, s := range searchFixed {
		searchBytes = append(searchBytes, []byte(s))
	}

	var errs []error
	for _, path := range searchPath {
		if err := search(path); err != nil {
			errs = append(errs, err)
		}
	}

	return errors.Join(errs...)
}

func recurse(path string) error {
	d, err := os.ReadDir(path)
	if err != nil {
		return err
	}

	var errs []error
NextFile:
	for _, de := range d {
		name := de.Name()
		fullPath := filepath.Join(path, name)

		for _, x := range excludeList {
			if exclude, _ := doublestar.Match(x, fullPath); exclude {
				continue NextFile
			}
		}

		if err := search(fullPath); err != nil {
			errs = append(errs, err)
		}
	}
	return errors.Join(errs...)
}

func search(path string) error {
	st, err := os.Stat(path)
	if err != nil {
		return err
	}

	switch {
	case st.IsDir():
		return recurse(path)

	case !st.Mode().IsRegular(),
		st.Size() == 0:
		return nil
	}

	f, err := os.Open(path)
	if err != nil {
		return err
	}
	defer f.Close()
	data, err := unix.Mmap(int(f.Fd()), 0, int(st.Size()), unix.PROT_READ, unix.MAP_PRIVATE)
	if err != nil {
		return err
	}
	defer unix.Munmap(data)

	file(path, data)
	return nil
}