package main

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

	"github.com/chzyer/readline"
)

// completer wires up Tab completion. Command names complete at the start of the
// line; cd/open/view complete local project names; clone/show complete
// repository names cached from the git server; checkout/tag complete branch and
// tag names; dist completes filesystem paths.
func completer() *readline.PrefixCompleter {
	return readline.NewPrefixCompleter(
		readline.PcItem("cd", readline.PcItemDynamic(dynLocalProjects)),
		readline.PcItem("open", readline.PcItemDynamic(dynLocalProjects)),
		readline.PcItem("view", readline.PcItemDynamic(dynLocalProjects)),
		readline.PcItem("clone",
			readline.PcItem("-a", readline.PcItemDynamic(dynServerArchives)),
			readline.PcItemDynamic(dynServerRepos),
		),
		readline.PcItem("cloneall"),
		readline.PcItem("show", readline.PcItemDynamic(dynServerRepos)),
		readline.PcItem("list", readline.PcItem("-a")),
		readline.PcItem("push"),
		readline.PcItem("pushremote"),
		readline.PcItem("pull"),
		readline.PcItem("fetch"),
		readline.PcItem("status", readline.PcItem("-a")),
		readline.PcItem("overview"),
		readline.PcItem("diff"),
		readline.PcItem("init"),
		readline.PcItem("edit"),
		readline.PcItem("checkout", readline.PcItemDynamic(dynCheckout)),
		readline.PcItem("log"),
		readline.PcItem("archive"),
		readline.PcItem("dist", readline.PcItemDynamic(dynPaths)),
		readline.PcItem("login"),
		readline.PcItem("count"),
		readline.PcItem("tag",
			readline.PcItem("add"),
			readline.PcItem("checkout", readline.PcItemDynamic(dynTags)),
			readline.PcItem("delete", readline.PcItemDynamic(dynTags)),
		),
		readline.PcItem("alias", readline.PcItemDynamic(dynAliasNames)),
		readline.PcItem("unalias", readline.PcItemDynamic(dynAliasNames)),
		readline.PcItem("rescan"),
		readline.PcItem("help"),
		readline.PcItem("quit"),
		readline.PcItem("exit"),
	)
}

// dynLocalProjects lists project directories under BASE (already name-sorted).
func dynLocalProjects(string) []string {
	entries, err := os.ReadDir(BASE)
	if err != nil {
		return nil
	}
	var out []string
	for _, e := range entries {
		if e.IsDir() && !strings.HasPrefix(e.Name(), ".") {
			out = append(out, e.Name())
		}
	}
	return out
}

var (
	serverRepos    []string
	serverArchives []string
	serverFetched  bool
)

// fetchServerRepos queries the server once and caches the repository/archive
// names for Tab completion.
func fetchServerRepos() {
	if serverFetched {
		return
	}
	serverFetched = true
	if lines, err := sshOut("/bin/ls ."); err == nil {
		for _, ln := range lines {
			if m := gitDirRe.FindStringSubmatch(strings.TrimSpace(ln)); m != nil {
				serverRepos = append(serverRepos, m[1])
			}
		}
	}
	if lines, err := sshOut("/bin/ls archive"); err == nil {
		for _, ln := range lines {
			t := strings.TrimSpace(ln)
			if strings.HasSuffix(t, ".git.tar.gz") {
				serverArchives = append(serverArchives, strings.TrimSuffix(t, ".git.tar.gz"))
			}
		}
	}
}

// rescanServer clears the cached server listing so the next completion (or use)
// re-fetches it.
func rescanServer() {
	serverFetched = false
	serverRepos = nil
	serverArchives = nil
}

func dynServerRepos(string) []string    { fetchServerRepos(); return serverRepos }
func dynServerArchives(string) []string { fetchServerRepos(); return serverArchives }

// dynBranches / dynTags list the active project's local branches / tags.
func dynBranches(string) []string {
	if !isDir(DIR + "/.git") {
		return nil
	}
	out, _ := gitCapture(DIR, "for-each-ref", "--format=%(refname:short)", "refs/heads")
	return splitLines(out)
}

func dynTags(string) []string {
	if !isDir(DIR + "/.git") {
		return nil
	}
	out, _ := gitCapture(DIR, "tag", "-l")
	return splitLines(out)
}

// dynCheckout offers both branches and tags for `checkout`.
func dynCheckout(line string) []string {
	return append(dynBranches(line), dynTags(line)...)
}

// dynPaths completes filesystem paths for the last token on the line.
func dynPaths(line string) []string {
	partial := ""
	if !strings.HasSuffix(line, " ") {
		if f := strings.Fields(line); len(f) > 0 {
			partial = f[len(f)-1]
		}
	}
	dir := "."
	if partial != "" {
		if strings.HasSuffix(partial, "/") {
			dir = partial
		} else {
			dir = filepath.Dir(partial)
		}
	}
	entries, err := os.ReadDir(dir)
	if err != nil {
		return nil
	}
	var out []string
	for _, e := range entries {
		if strings.HasPrefix(e.Name(), ".") {
			continue
		}
		p := filepath.Join(dir, e.Name())
		if e.IsDir() {
			p += "/"
		}
		out = append(out, p)
	}
	return out
}