package api

// Stacks: the compose projects behind the containers, with their files to edit and a way to
// redeploy them.
//
// A stack is found from its containers' labels (project, config file). The file may not be
// where the label says: an orchestrator that runs compose from inside its own container —
// Dockhand, Dockge, Portainer — records a path in *its* filesystem. So the path is looked
// up twice: as it stands on this host, and through every container's mounts
// (/app/data/stacks/… in `dockhand` is /home/core/apps/dockhand/stacks/… here). Compose is
// then run where the file makes sense — inside that container when it came from one, so
// relative paths, the .env beside it and the labels all stay exactly as they were deployed —
// else on the host. A stack whose file is on no path this machine can see (deployed from
// another host over tcp) is listed read-only, and says so.

import (
	"bytes"
	"context"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
	"time"

	"hamlab/internal/priv"
)

type stack struct {
	Name       string   `json:"name"`
	Containers []string `json:"containers"`
	Running    int      `json:"running"`
	File       string   `json:"file"`       // as the label has it (the first of Files)
	HostFile   string   `json:"host_file"`  // where it is on this machine; "" when it isn't
	Files      []string `json:"files"`      // every file it was deployed from, in order: -f a -f b
	HostFiles  []string `json:"host_files"` // the same, on this machine
	Via        string   `json:"via"`        // container compose runs inside; "" = on the host
	Editable   bool     `json:"editable"`
	Note       string   `json:"note,omitempty"`
	HasEnv     bool     `json:"has_env"`
}

type mountMap struct{ container, dest, src string }

func stackMounts(ctx context.Context) []mountMap {
	out, err := dockerRun(ctx, "ps", "-q")
	if err != nil || len(bytes.TrimSpace(out)) == 0 {
		return nil
	}
	insp, err := dockerRun(ctx, append([]string{"inspect"}, strings.Fields(string(out))...)...)
	if err != nil {
		return nil
	}
	var list []struct {
		Name   string
		Mounts []struct{ Type, Source, Destination string }
	}
	if json.Unmarshal(insp, &list) != nil {
		return nil
	}
	var maps []mountMap
	for _, c := range list {
		for _, m := range c.Mounts {
			if m.Type == "bind" && m.Destination != "/" && m.Source != "" {
				maps = append(maps, mountMap{strings.TrimPrefix(c.Name, "/"), filepath.Clean(m.Destination), filepath.Clean(m.Source)})
			}
		}
	}
	sort.Slice(maps, func(i, j int) bool { return len(maps[i].dest) > len(maps[j].dest) }) // the most specific mount wins
	return maps
}

func readable(p string) bool {
	if _, err := os.Stat(p); err == nil {
		return true
	}
	if priv.Available() { // stacks kept by a root-owned orchestrator are often unreadable to us
		full := priv.Wrap("test", "-f", p)
		return exec.Command(full[0], full[1:]...).Run() == nil
	}
	return false
}

func (s *Server) findStacks(ctx context.Context) ([]stack, error) {
	// Labels come from inspect, not `ps`: ps joins every label with commas, and the label that
	// matters here — the list of compose files — is itself a comma-separated list.
	ids, err := dockerRun(ctx, "ps", "-aq")
	if err != nil {
		return nil, err
	}
	by := map[string]*stack{}
	if len(bytes.TrimSpace(ids)) > 0 {
		const f = `{{.Name}}|{{.State.Status}}|{{index .Config.Labels "com.docker.compose.project"}}|{{index .Config.Labels "com.docker.compose.project.config_files"}}`
		out, err := dockerRun(ctx, append([]string{"inspect", "-f", f}, strings.Fields(string(ids))...)...)
		if err != nil {
			return nil, err
		}
		for _, line := range strings.Split(strings.TrimSpace(string(out)), "\n") {
			p := strings.SplitN(line, "|", 4)
			if len(p) < 4 || p[2] == "" {
				continue
			}
			st := by[p[2]]
			if st == nil {
				st = &stack{Name: p[2]}
				if p[3] != "" {
					st.Files = strings.Split(p[3], ",")
					st.File = st.Files[0]
				}
				by[p[2]] = st
			}
			st.Containers = append(st.Containers, strings.TrimPrefix(p[0], "/"))
			if p[1] == "running" {
				st.Running++
			}
		}
	}
	maps := stackMounts(ctx)
	stacks := []stack{}
	for _, st := range by {
		sort.Strings(st.Containers)
		// Every file must be found — a stack deployed from `-f compose.yaml -f override.yaml` and
		// redeployed from the first alone would quietly lose everything the override set.
		resolve := func(f string) (host, via string) {
			if readable(f) {
				return f, ""
			}
			for _, m := range maps {
				if rest, ok := strings.CutPrefix(f, m.dest+"/"); ok && readable(filepath.Join(m.src, rest)) {
					return filepath.Join(m.src, rest), m.container
				}
			}
			return "", ""
		}
		if st.File == "" {
			st.Note = "its containers don't say which file deployed them"
		} else {
			for i, f := range st.Files {
				host, via := resolve(f)
				if host == "" || (i > 0 && via != st.Via) {
					st.HostFiles, st.Via = nil, ""
					st.Note = "deployed from somewhere this machine can't see (" + f + "); edit it there"
					break
				}
				st.HostFiles, st.Via = append(st.HostFiles, host), via
			}
			if len(st.HostFiles) > 0 {
				st.HostFile = st.HostFiles[0]
			}
		}
		if st.HostFile != "" {
			st.Editable = true
			st.HasEnv = readable(filepath.Join(filepath.Dir(st.HostFile), ".env"))
		}
		stacks = append(stacks, *st)
	}
	sort.Slice(stacks, func(i, j int) bool { return stacks[i].Name < stacks[j].Name })
	return stacks, nil
}

func (s *Server) stackByName(ctx context.Context, name string) (stack, error) {
	all, err := s.findStacks(ctx)
	if err != nil {
		return stack{}, err
	}
	for _, st := range all {
		if st.Name == name {
			return st, nil
		}
	}
	return stack{}, errors.New("no such stack")
}

func (s *Server) stacksList(w http.ResponseWriter, r *http.Request) {
	ctx, cancel := context.WithTimeout(r.Context(), 30*time.Second)
	defer cancel()
	if dockerTool() == "" { // no Docker is an empty answer, not a failure
		jsonOK(w, 200, map[string]any{"stacks": []stack{}})
		return
	}
	stacks, err := s.findStacks(ctx)
	if err != nil {
		jsonErr(w, 500, err.Error())
		return
	}
	jsonOK(w, 200, map[string]any{"stacks": stacks})
}

func readAsRoot(ctx context.Context, path string) ([]byte, error) {
	b, err := os.ReadFile(path)
	if err != nil && priv.Available() {
		full := priv.Wrap("cat", path)
		b, err = exec.CommandContext(ctx, full[0], full[1:]...).Output()
	}
	return b, err
}

func sumOf(b []byte) string { h := sha256.Sum256(b); return hex.EncodeToString(h[:8]) }

// fileIndex is which of the stack's files a request means: ?file=1 is the first override.
func fileIndex(r *http.Request, st stack) (int, bool) {
	i, err := strconv.Atoi(r.URL.Query().Get("file"))
	if r.URL.Query().Get("file") == "" {
		return 0, true
	}
	return i, err == nil && i >= 0 && i < len(st.HostFiles)
}

func (s *Server) stackFile(w http.ResponseWriter, r *http.Request) {
	ctx, cancel := context.WithTimeout(r.Context(), 30*time.Second)
	defer cancel()
	st, err := s.stackByName(ctx, r.PathValue("name"))
	if err != nil || !st.Editable {
		jsonErr(w, 404, "that stack's compose file isn't on this machine")
		return
	}
	i, ok := fileIndex(r, st)
	if !ok {
		jsonErr(w, 400, "no such file in this stack")
		return
	}
	b, err := readAsRoot(ctx, st.HostFiles[i])
	if err != nil {
		jsonErr(w, 500, err.Error())
		return
	}
	// sum is what the editor hands back when it saves, so a file changed meanwhile is noticed
	jsonOK(w, 200, map[string]any{"stack": st, "text": string(b), "sum": sumOf(b), "index": i})
}

// composeCmd is `docker compose …` for this stack, run where its file makes sense.
// files are given as compose will see them: the label's paths inside a container, host paths otherwise.
func composeCmd(ctx context.Context, st stack, files []string, args ...string) *exec.Cmd {
	tool := dockerTool()
	base := []string{"compose", "-p", st.Name}
	for _, f := range files {
		base = append(base, "-f", f)
	}
	if st.Via != "" {
		return exec.CommandContext(ctx, tool, append(append([]string{"exec", st.Via, "docker"}, base...), args...)...)
	}
	cmd := exec.CommandContext(ctx, tool, append(base, args...)...)
	cmd.Dir = filepath.Dir(files[0])
	return cmd
}

// seenFiles is the stack's file list as compose runs it, with file i replaced by a candidate.
func seenFiles(st stack, i int, candidate string) []string {
	out := append([]string{}, st.HostFiles...)
	if st.Via != "" {
		out = append([]string{}, st.Files...)
	}
	if i >= 0 {
		out[i] = candidate
	}
	return out
}

// stackSave validates the new text with compose itself, keeps the old file beside it as
// <file>.hamlab-bak, and writes. It does not deploy: that is its own button.
func (s *Server) stackSave(w http.ResponseWriter, r *http.Request) {
	ctx, cancel := context.WithTimeout(r.Context(), 60*time.Second)
	defer cancel()
	st, err := s.stackByName(ctx, r.PathValue("name"))
	if err != nil || !st.Editable {
		jsonErr(w, 404, "that stack's compose file isn't on this machine")
		return
	}
	var body struct {
		Text string `json:"text"`
		Sum  string `json:"sum"` // the sum the editor was given when it opened the file
	}
	if err := json.NewDecoder(io.LimitReader(r.Body, 1<<20)).Decode(&body); err != nil || strings.TrimSpace(body.Text) == "" {
		jsonErr(w, 400, "the file can't be empty")
		return
	}
	i, ok := fileIndex(r, st)
	if !ok {
		jsonErr(w, 400, "no such file in this stack")
		return
	}
	target := st.HostFiles[i]
	if now, err := readAsRoot(ctx, target); err == nil && body.Sum != "" && sumOf(now) != body.Sum {
		jsonErr(w, 409, "the file has changed on disk since you opened it (Dockhand, or another editor). Reload it to see the change; your text is still in the box.")
		return
	}
	// Validate a candidate beside the real file, so `.env` and relative paths resolve as they will.
	cand := target + ".hamlab-new"
	err = s.fsLocal.Write(ctx, cand, strings.NewReader(body.Text)) // ours to write, or root's
	if err != nil {
		err = s.fsSudo.Write(ctx, cand, strings.NewReader(body.Text))
	}
	if err != nil {
		jsonErr(w, 500, "couldn't write beside the compose file: "+err.Error())
		return
	}
	inner := cand
	if st.Via != "" {
		inner = st.Files[i] + ".hamlab-new"
	}
	if msg, err := composeCmd(ctx, st, seenFiles(st, i, inner), "config", "-q").CombinedOutput(); err != nil {
		_ = s.fsSudo.Delete(ctx, cand, false)
		jsonErr(w, 400, "compose rejects it: "+strings.TrimSpace(string(msg)))
		return
	}
	for _, mv := range [][]string{{"cp", "-p", target, target + ".hamlab-bak"}, {"mv", cand, target}} {
		full := priv.Wrap(mv...)
		if msg, err := exec.CommandContext(ctx, full[0], full[1:]...).CombinedOutput(); err != nil {
			jsonErr(w, 500, strings.TrimSpace(string(msg)))
			return
		}
	}
	log.Printf("stack %s: compose file saved (from %s)", st.Name, clientIP(r))
	w.WriteHeader(204)
}

// stackAction runs deploy (up -d), update (pull, then up -d), restart or stop as a task
// whose output the page follows.
func (s *Server) stackAction(w http.ResponseWriter, r *http.Request) {
	ctx, cancel := context.WithTimeout(r.Context(), 30*time.Second)
	defer cancel()
	st, err := s.stackByName(ctx, r.PathValue("name"))
	if err != nil || !st.Editable {
		jsonErr(w, 404, "that stack's compose file isn't on this machine")
		return
	}
	files := seenFiles(st, -1, "")
	var fl []string
	for _, f := range files {
		fl = append(fl, "-f", f)
	}
	flags := priv.Quote(append([]string{"-p", st.Name}, fl...))
	var script string
	base := func(args string) string {
		if st.Via != "" {
			return fmt.Sprintf("%s exec %s docker compose %s %s", dockerTool(), priv.Quote([]string{st.Via}), flags, args)
		}
		return fmt.Sprintf("cd %s && %s compose %s %s", priv.Quote([]string{filepath.Dir(files[0])}), dockerTool(), flags, args)
	}
	switch r.PathValue("action") {
	case "deploy":
		script = base("up -d --remove-orphans")
	case "update":
		script = base("pull") + " && " + base("up -d --remove-orphans")
	case "restart":
		script = base("restart")
	case "stop":
		script = base("stop")
	default:
		jsonErr(w, 400, "deploy, update, restart or stop")
		return
	}
	if t, busy := s.tasks.RunningOf("stack:" + st.Name); busy {
		jsonErr(w, 409, "this stack is already busy (task "+t.ID+")")
		return
	}
	t, err := s.tasks.Start("stack:"+st.Name, r.PathValue("action")+" "+st.Name, exec.Command("sh", "-c", script+" 2>&1"))
	if err != nil {
		jsonErr(w, 500, err.Error())
		return
	}
	log.Printf("stack %s: %s started as task %s (from %s)", st.Name, r.PathValue("action"), t.ID, clientIP(r))
	jsonOK(w, 202, t.Snapshot(false))
}