package main

import (
	"bytes"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"path"
	"path/filepath"
	"strings"
	"time"

	"github.com/calmh/syncthing/protocol"
)

const BlockSize = 128 * 1024

type File struct {
	Name     string
	Flags    uint32
	Modified int64
	Version  uint32
	Blocks   []Block
}

func (f File) Size() (bytes int) {
	for _, b := range f.Blocks {
		bytes += int(b.Size)
	}
	return
}

func (f File) String() string {
	return fmt.Sprintf("File{Name:%q, Flags:0x%x, Modified:%d, Version:%d, NumBlocks:%d}",
		f.Name, f.Flags, f.Modified, f.Version, len(f.Blocks))
}

func (f File) Equals(o File) bool {
	return f.Modified == o.Modified && f.Version == o.Version
}

func (f File) NewerThan(o File) bool {
	return f.Modified > o.Modified || (f.Modified == o.Modified && f.Version > o.Version)
}

func isTempName(name string) bool {
	return strings.HasPrefix(path.Base(name), ".syncthing.")
}

func tempName(name string, modified int64) string {
	tdir := path.Dir(name)
	tname := fmt.Sprintf(".syncthing.%s.%d", path.Base(name), modified)
	return path.Join(tdir, tname)
}

func (m *Model) loadIgnoreFiles(ign map[string][]string) filepath.WalkFunc {
	return func(p string, info os.FileInfo, err error) error {
		if err != nil {
			return nil
		}

		rn, err := filepath.Rel(m.dir, p)
		if err != nil {
			return nil
		}

		if pn, sn := path.Split(rn); sn == ".stignore" {
			pn := strings.Trim(pn, "/")
			bs, _ := ioutil.ReadFile(p)
			lines := bytes.Split(bs, []byte("\n"))
			var patterns []string
			for _, line := range lines {
				if len(line) > 0 {
					patterns = append(patterns, string(line))
				}
			}
			ign[pn] = patterns
		}

		return nil
	}
}

func (m *Model) walkAndHashFiles(res *[]File, ign map[string][]string) filepath.WalkFunc {
	return func(p string, info os.FileInfo, err error) error {
		if err != nil {
			if m.trace["file"] {
				log.Printf("FILE: %q: %v", p, err)
			}
			return nil
		}

		if isTempName(p) {
			return nil
		}

		rn, err := filepath.Rel(m.dir, p)
		if err != nil {
			return nil
		}

		if _, sn := path.Split(rn); sn == ".stignore" {
			// We never sync the .stignore files
			return nil
		}

		if ignoreFile(ign, rn) {
			if m.trace["file"] {
				log.Println("FILE: IGNORE:", rn)
			}
			return nil
		}

		if info.Mode()&os.ModeType == 0 {
			modified := info.ModTime().Unix()

			m.lmut.RLock()
			lf, ok := m.local[rn]
			m.lmut.RUnlock()

			if ok && lf.Modified == modified {
				if nf := uint32(info.Mode()); nf != lf.Flags {
					lf.Flags = nf
					lf.Version++
				}
				*res = append(*res, lf)
			} else {
				if cur, prev := m.sup.suppress(rn, info.Size(), time.Now()); cur {
					if m.trace["file"] {
						log.Printf("FILE: SUPPRESS: %q change bw over threshold", rn)
					}
					if !prev {
						log.Printf("INFO: Changes to %q are being temporarily suppressed because it changes too frequently.", rn)
					}

					if ok {
						lf.Flags = protocol.FlagInvalid
						lf.Version++
						*res = append(*res, lf)
					}
					return nil
				} else if prev && !cur {
					log.Printf("INFO: Changes to %q are no longer suppressed.", rn)
				}

				if m.trace["file"] {
					log.Printf("FILE: Hash %q", p)
				}
				fd, err := os.Open(p)
				if err != nil {
					if m.trace["file"] {
						log.Printf("FILE: %q: %v", p, err)
					}
					return nil
				}
				defer fd.Close()

				blocks, err := Blocks(fd, BlockSize)
				if err != nil {
					if m.trace["file"] {
						log.Printf("FILE: %q: %v", p, err)
					}
					return nil
				}
				f := File{
					Name:     rn,
					Flags:    uint32(info.Mode()),
					Modified: modified,
					Blocks:   blocks,
				}
				*res = append(*res, f)
			}
		}

		return nil
	}
}

// Walk returns the list of files found in the local repository by scanning the
// file system. Files are blockwise hashed.
func (m *Model) Walk(followSymlinks bool) (files []File, ignore map[string][]string) {
	ignore = make(map[string][]string)

	hashFiles := m.walkAndHashFiles(&files, ignore)

	filepath.Walk(m.dir, m.loadIgnoreFiles(ignore))
	filepath.Walk(m.dir, hashFiles)

	if followSymlinks {
		d, err := os.Open(m.dir)
		if err != nil {
			return
		}
		defer d.Close()

		fis, err := d.Readdir(-1)
		if err != nil {
			return
		}

		for _, info := range fis {
			if info.Mode()&os.ModeSymlink != 0 {
				dir := path.Join(m.dir, info.Name()) + "/"
				filepath.Walk(dir, m.loadIgnoreFiles(ignore))
				filepath.Walk(dir, hashFiles)
			}
		}
	}

	return
}

func (m *Model) cleanTempFile(path string, info os.FileInfo, err error) error {
	if err != nil {
		return err
	}
	if info.Mode()&os.ModeType == 0 && isTempName(path) {
		if m.trace["file"] {
			log.Printf("FILE: Remove %q", path)
		}
		os.Remove(path)
	}
	return nil
}

func (m *Model) cleanTempFiles() {
	filepath.Walk(m.dir, m.cleanTempFile)
}

func ignoreFile(patterns map[string][]string, file string) bool {
	first, last := path.Split(file)
	for prefix, pats := range patterns {
		if len(prefix) == 0 || prefix == first || strings.HasPrefix(first, prefix+"/") {
			for _, pattern := range pats {
				if match, _ := path.Match(pattern, last); match {
					return true
				}
			}
		}
	}
	return false
}