package hammerhead

import (
	"errors"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"time"
)

const maxUpdateLines = 200

// updRun is the progress of one update an edge or site is carrying out, as that agent reported it.
type updRun struct {
	ID    string // the update request it belongs to
	Stage string
	Pct   int
	Lines []string
}

// recordUpdateProgress keeps what an agent says about the update it is running. When the agent
// reports a new version, the update is finished: its log gets a closing line and is then left alone,
// so the freshly restarted program (which starts a new, empty log) can't overwrite it.
// Caller holds s.mu.
func (s *Server) recordUpdateProgress(agentID, reqID, stage string, pct int, lines []string, oldVersion, newVersion string) {
	run := s.updRuns[agentID]
	if run != nil && run.Stage != "done" && oldVersion != "" && newVersion != "" && newVersion != oldVersion {
		run.Lines = append(run.Lines, time.Now().Format("15:04:05")+" Now running "+newVersion)
		run.Stage, run.Pct = "done", 100
		return
	}
	if reqID == "" || (stage == "" && len(lines) == 0) {
		return
	}
	if run != nil && run.ID == reqID && run.Stage == "done" {
		return
	}
	s.updRuns[agentID] = &updRun{ID: reqID, Stage: stage, Pct: pct, Lines: lines}
}

func (s *Server) updateLogView(agentID string, pending bool, msg, version string) map[string]any {
	out := map[string]any{"running": pending, "msg": msg, "version": version, "stage": "", "pct": 0, "lines": []string{}}
	if run := s.updRuns[agentID]; run != nil {
		out["stage"], out["pct"], out["lines"] = run.Stage, run.Pct, run.Lines
	}
	return out
}

func (s *Server) edgeUpdateLog(w http.ResponseWriter, r *http.Request, p *principal) {
	s.mu.Lock()
	defer s.mu.Unlock()
	e := s.findEdge(r.PathValue("id"))
	if e == nil {
		fail(w, 404, errors.New("no such edge"))
		return
	}
	writeJSON(w, 200, s.updateLogView(e.ID, e.UpdateID != "", e.UpdateMsg, e.Version))
}

func (s *Server) siteUpdateLog(w http.ResponseWriter, r *http.Request, c *orgCtx) {
	s.mu.Lock()
	defer s.mu.Unlock()
	st := s.findSite(r.PathValue("id"))
	if st == nil || !s.siteVisible(c, st) {
		fail(w, 404, errors.New("no such site"))
		return
	}
	writeJSON(w, 200, s.updateLogView(st.ID, st.UpdateID != "", st.UpdateMsg, st.Version))
}

// selfUpdate is the progress of this server's own update. It is kept in memory and in <data>/update.log,
// so the page can still show it after the restart that ends a successful update.
type selfUpdate struct {
	mu      sync.Mutex
	running bool
	stage   string
	pct     int
	lines   []string
}

func (s *Server) updateLogPath() string { return filepath.Join(s.dir, "update.log") }

func (s *Server) selfNote(stage string, pct int, line string) {
	u := &s.selfUpd
	u.mu.Lock()
	defer u.mu.Unlock()
	if stage != "" {
		u.stage = stage
	}
	if pct >= 0 {
		u.pct = pct
	}
	if line == "" {
		return
	}
	line = time.Now().Format("15:04:05") + " " + line
	u.lines = append(u.lines, line)
	if len(u.lines) > maxUpdateLines {
		u.lines = u.lines[len(u.lines)-maxUpdateLines:]
	}
	if f, err := os.OpenFile(s.updateLogPath(), os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o600); err == nil {
		f.WriteString(line + "\n")
		f.Close()
	}
}

func readLines(path string) []string {
	b, err := os.ReadFile(path)
	if err != nil {
		return nil
	}
	lines := strings.Split(strings.TrimRight(string(b), "\n"), "\n")
	if len(lines) == 1 && lines[0] == "" {
		return nil
	}
	if len(lines) > maxUpdateLines {
		lines = lines[len(lines)-maxUpdateLines:]
	}
	return lines
}

// finishSelfUpdateLog runs at startup: if the last run ended by restarting into this process, say so.
func (s *Server) finishSelfUpdateLog() {
	lines := readLines(s.updateLogPath())
	if n := len(lines); n > 0 && strings.Contains(lines[n-1], "restarting") && s.opts.Version != "" {
		if f, err := os.OpenFile(s.updateLogPath(), os.O_APPEND|os.O_WRONLY, 0o600); err == nil {
			f.WriteString(time.Now().Format("15:04:05") + " Hammerhead restarted: now running " + s.opts.Version + "\n")
			f.Close()
		}
	}
}

// updateStatus returns the progress and log of this server's own update, for the Settings page.
func (s *Server) updateStatus(w http.ResponseWriter, r *http.Request, p *principal) {
	u := &s.selfUpd
	u.mu.Lock()
	out := map[string]any{"running": u.running, "stage": u.stage, "pct": u.pct, "lines": append([]string(nil), u.lines...), "version": s.opts.Version}
	u.mu.Unlock()
	if lines, _ := out["lines"].([]string); len(lines) == 0 {
		// nothing in memory: this is a fresh process, so show the last update's log from disk
		if saved := readLines(s.updateLogPath()); len(saved) > 0 {
			stage := "done"
			if strings.Contains(saved[len(saved)-1], "Failed:") {
				stage = "failed"
			}
			out["lines"], out["stage"], out["pct"] = saved, stage, 100
		}
	}
	writeJSON(w, 200, out)
}