package ui

import (
	"database/sql"
	"embed"
	"encoding/json"
	"html/template"
	"log"
	"net/http"
	"os"
	"strconv"
	"time"

	_ "github.com/go-sql-driver/mysql"
	appdb "github.com/vandachevici/ha-sync/internal/db"
	"github.com/vandachevici/ha-sync/internal/kube"
	"k8s.io/client-go/kubernetes"
)

//go:embed templates/index.html templates/about.html
var templateFS embed.FS

var indexTmpl = template.Must(template.ParseFS(templateFS, "templates/index.html"))
var aboutTmpl = template.Must(template.ParseFS(templateFS, "templates/about.html"))

// Server holds the database connection and serves the dashboard.
type Server struct {
	db         *sql.DB
	kubeClient kubernetes.Interface
	namespace  string
}

func NewServer(sqlDB *sql.DB) *Server {
	ns := os.Getenv("HA_SYNC_NAMESPACE")
	if ns == "" {
		ns = "ha-sync"
	}
	s := &Server{db: sqlDB, namespace: ns}
	client, err := kube.NewClient()
	if err != nil {
		log.Printf("ha-sync-ui: kube unavailable, kube features disabled: %v", err)
	} else {
		s.kubeClient = client
	}
	return s
}

// Handler wires all routes and returns the mux.
func (s *Server) Handler() http.Handler {
	mux := http.NewServeMux()

	// Existing routes (preserved).
	mux.HandleFunc("GET /", s.handleIndex)
	mux.HandleFunc("GET /about", s.handleAbout)
	mux.HandleFunc("GET /health", s.handleHealth)
	mux.HandleFunc("GET /api/pairs", s.handlePairs)
	mux.HandleFunc("GET /api/iterations", s.handleIterations)
	mux.HandleFunc("GET /api/operations", s.handleOperations)

	// Job management API.
	mux.HandleFunc("GET /api/jobs", s.handleListJobs)
	mux.HandleFunc("POST /api/jobs", s.handleCreateJob)
	mux.HandleFunc("GET /api/jobs/{id}", s.handleGetJob)
	mux.HandleFunc("PUT /api/jobs/{id}", s.handleUpdateJob)
	mux.HandleFunc("DELETE /api/jobs/{id}", s.handleDeleteJob)
	mux.HandleFunc("POST /api/jobs/{id}/enable", s.handleEnableJob)
	mux.HandleFunc("POST /api/jobs/{id}/disable", s.handleDisableJob)
	mux.HandleFunc("POST /api/jobs/{id}/trigger", s.handleTriggerJob)
	mux.HandleFunc("GET /api/jobs/{id}/lock", s.handleGetLockStatus)

	// Run operations.
	mux.HandleFunc("GET /api/runs/{runID}/ops", s.handleListOps)

	return mux
}

// --- helpers ---

// jobDetailResp combines a job with its recent iterations for the GET /api/jobs/{id} response.
type jobDetailResp struct {
	*appdb.Job
	Iterations []*appdb.Iteration `json:"iterations"`
}

func parseJobID(r *http.Request) (int64, bool) {
	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	return id, err == nil
}

func jobToSpec(j *appdb.Job) kube.JobSpec {
	return kube.JobSpec{
		ID:             j.ID,
		Name:           j.Name,
		Pair:           j.Pair,
		Direction:      j.Direction,
		Src:            j.Src,
		Dest:           j.Dest,
		SrcHost:        j.SrcHost,
		DestHost:       j.DestHost,
		CronSchedule:   j.CronSchedule,
		LockTTLSeconds: j.LockTTLSeconds,
		DryRun:         j.DryRun,
		DeleteMissing:  j.DeleteMissing,
		Workers:        j.Workers,
		MtimeThreshold: j.MtimeThreshold,
		Excludes:       j.Excludes,
		Enabled:        j.Enabled,
	}
}

// --- new job API handlers ---

func (s *Server) handleListJobs(w http.ResponseWriter, r *http.Request) {
	jobs, err := appdb.ListJobsWithStats(s.db)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	if jobs == nil {
		jobs = []*appdb.JobWithStats{}
	}
	writeJSON(w, jobs)
}

func (s *Server) handleCreateJob(w http.ResponseWriter, r *http.Request) {
	var input appdb.JobInput
	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
		writeError(w, http.StatusBadRequest, "invalid JSON: "+err.Error())
		return
	}
	job, err := appdb.CreateJob(s.db, input)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	if s.kubeClient != nil {
		if err := kube.ApplyCronJob(r.Context(), s.kubeClient, s.namespace, jobToSpec(job)); err != nil {
			log.Printf("ha-sync-ui: apply cronjob for %s: %v", job.Name, err)
		}
	}
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)
	json.NewEncoder(w).Encode(job)
}

func (s *Server) handleGetJob(w http.ResponseWriter, r *http.Request) {
	id, ok := parseJobID(r)
	if !ok {
		writeError(w, http.StatusBadRequest, "invalid id")
		return
	}
	job, err := appdb.GetJobByID(s.db, id)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	if job == nil {
		writeError(w, http.StatusNotFound, "job not found")
		return
	}
	iters, err := appdb.ListIterations(s.db, job.Pair, job.Direction, 50)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	if iters == nil {
		iters = []*appdb.Iteration{}
	}
	writeJSON(w, jobDetailResp{Job: job, Iterations: iters})
}

func (s *Server) handleUpdateJob(w http.ResponseWriter, r *http.Request) {
	id, ok := parseJobID(r)
	if !ok {
		writeError(w, http.StatusBadRequest, "invalid id")
		return
	}
	var input appdb.JobInput
	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
		writeError(w, http.StatusBadRequest, "invalid JSON: "+err.Error())
		return
	}
	job, err := appdb.UpdateJob(s.db, id, input)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	if job == nil {
		writeError(w, http.StatusNotFound, "job not found")
		return
	}
	if s.kubeClient != nil {
		if err := kube.ApplyCronJob(r.Context(), s.kubeClient, s.namespace, jobToSpec(job)); err != nil {
			log.Printf("ha-sync-ui: re-apply cronjob for %s: %v", job.Name, err)
		}
	}
	writeJSON(w, job)
}

func (s *Server) handleDeleteJob(w http.ResponseWriter, r *http.Request) {
	id, ok := parseJobID(r)
	if !ok {
		writeError(w, http.StatusBadRequest, "invalid id")
		return
	}
	job, err := appdb.GetJobByID(s.db, id)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	if job == nil {
		writeError(w, http.StatusNotFound, "job not found")
		return
	}
	if s.kubeClient != nil {
		if err := kube.DeleteCronJob(r.Context(), s.kubeClient, s.namespace, job.Name); err != nil {
			log.Printf("ha-sync-ui: delete cronjob for %s: %v", job.Name, err)
		}
	}
	if err := appdb.DeleteJob(s.db, id); err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

func (s *Server) handleEnableJob(w http.ResponseWriter, r *http.Request) {
	id, ok := parseJobID(r)
	if !ok {
		writeError(w, http.StatusBadRequest, "invalid id")
		return
	}
	if err := appdb.SetJobEnabled(s.db, id, true); err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	job, _ := appdb.GetJobByID(s.db, id)
	if s.kubeClient != nil && job != nil {
		if err := kube.SuspendCronJob(r.Context(), s.kubeClient, s.namespace, job.Name, false); err != nil {
			log.Printf("ha-sync-ui: unsuspend cronjob for %s: %v", job.Name, err)
		}
	}
	writeJSON(w, map[string]bool{"ok": true})
}

func (s *Server) handleDisableJob(w http.ResponseWriter, r *http.Request) {
	id, ok := parseJobID(r)
	if !ok {
		writeError(w, http.StatusBadRequest, "invalid id")
		return
	}
	if err := appdb.SetJobEnabled(s.db, id, false); err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	job, _ := appdb.GetJobByID(s.db, id)
	if s.kubeClient != nil && job != nil {
		if err := kube.SuspendCronJob(r.Context(), s.kubeClient, s.namespace, job.Name, true); err != nil {
			log.Printf("ha-sync-ui: suspend cronjob for %s: %v", job.Name, err)
		}
	}
	writeJSON(w, map[string]bool{"ok": true})
}

func (s *Server) handleTriggerJob(w http.ResponseWriter, r *http.Request) {
	id, ok := parseJobID(r)
	if !ok {
		writeError(w, http.StatusBadRequest, "invalid id")
		return
	}
	if s.kubeClient == nil {
		writeError(w, http.StatusServiceUnavailable, "kube client unavailable")
		return
	}
	job, err := appdb.GetJobByID(s.db, id)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	if job == nil {
		writeError(w, http.StatusNotFound, "job not found")
		return
	}
	jobName, err := kube.TriggerJob(r.Context(), s.kubeClient, s.namespace, job.Name)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	writeJSON(w, map[string]string{"job_name": jobName})
}

func (s *Server) handleGetLockStatus(w http.ResponseWriter, r *http.Request) {
	id, ok := parseJobID(r)
	if !ok {
		writeError(w, http.StatusBadRequest, "invalid id")
		return
	}
	if s.kubeClient == nil {
		writeError(w, http.StatusServiceUnavailable, "kube client unavailable")
		return
	}
	job, err := appdb.GetJobByID(s.db, id)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	if job == nil {
		writeError(w, http.StatusNotFound, "job not found")
		return
	}
	status, err := kube.GetLockStatus(r.Context(), s.kubeClient, s.namespace, job.Name)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	writeJSON(w, status)
}

func (s *Server) handleListOps(w http.ResponseWriter, r *http.Request) {
	runID, err := strconv.ParseInt(r.PathValue("runID"), 10, 64)
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid run id")
		return
	}
	q := r.URL.Query()
	limit := 200
	offset := 0
	if l := q.Get("limit"); l != "" {
		if n, e := strconv.Atoi(l); e == nil && n > 0 {
			limit = n
		}
	}
	if o := q.Get("offset"); o != "" {
		if n, e := strconv.Atoi(o); e == nil && n >= 0 {
			offset = n
		}
	}
	ops, total, err := appdb.ListOperations(s.db, runID, limit, offset)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	if ops == nil {
		ops = []*appdb.OperationRow{}
	}
	writeJSON(w, map[string]any{
		"total":      total,
		"operations": ops,
	})
}

// --- response types (legacy endpoints) ---

type Iteration struct {
	ID                   int64      `json:"id"`
	SyncPair             string     `json:"sync_pair"`
	Direction            string     `json:"direction"`
	Status               string     `json:"status"`
	DryRun               bool       `json:"dry_run"`
	StartedAt            time.Time  `json:"started_at"`
	EndedAt              *time.Time `json:"ended_at"`
	FilesCreated         int        `json:"files_created"`
	FilesUpdated         int        `json:"files_updated"`
	FilesDeleted         int        `json:"files_deleted"`
	FilesSkipped         int        `json:"files_skipped"`
	FilesFailed          int        `json:"files_failed"`
	TotalBytesTransferred int64     `json:"total_bytes_transferred"`
	ErrorMessage         *string    `json:"error_message,omitempty"`
}

type PairSummary struct {
	Pair         string     `json:"pair"`
	LastRealSync *Iteration `json:"last_real_sync"`
	LastDryRun   *Iteration `json:"last_dry_run"`
}

type Operation struct {
	ID           int64      `json:"id"`
	IterationID  int64      `json:"iteration_id"`
	DryRun       bool       `json:"dry_run"`
	Operation    string     `json:"operation"`
	Filepath     string     `json:"filepath"`
	SizeBefore   *int64     `json:"size_before,omitempty"`
	SizeAfter    *int64     `json:"size_after,omitempty"`
	Md5Before    *string    `json:"md5_before,omitempty"`
	Md5After     *string    `json:"md5_after,omitempty"`
	StartedAt    time.Time  `json:"started_at"`
	EndedAt      *time.Time `json:"ended_at,omitempty"`
	Status       string     `json:"status"`
	ErrorMessage *string    `json:"error_message,omitempty"`
}

// --- handlers ---

func (s *Server) handleAbout(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := aboutTmpl.Execute(w, nil); err != nil {
		http.Error(w, "template error", http.StatusInternalServerError)
	}
}

func (s *Server) handleIndex(w http.ResponseWriter, r *http.Request) {
	if r.URL.Path != "/" {
		http.NotFound(w, r)
		return
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := indexTmpl.Execute(w, nil); err != nil {
		http.Error(w, "template error", http.StatusInternalServerError)
	}
}

func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
	writeJSON(w, map[string]string{"status": "ok"})
}

func (s *Server) handlePairs(w http.ResponseWriter, r *http.Request) {
	rows, err := s.db.QueryContext(r.Context(),
		`SELECT DISTINCT sync_pair FROM sync_iterations ORDER BY sync_pair`)
	if err != nil {
		httpError(w, err)
		return
	}
	defer rows.Close()

	var pairs []string
	for rows.Next() {
		var p string
		if err := rows.Scan(&p); err != nil {
			httpError(w, err)
			return
		}
		pairs = append(pairs, p)
	}
	if err := rows.Err(); err != nil {
		httpError(w, err)
		return
	}

	summaries := make([]PairSummary, 0, len(pairs))
	for _, pair := range pairs {
		real, err := s.latestIteration(r, pair, false)
		if err != nil {
			httpError(w, err)
			return
		}
		dry, err := s.latestIteration(r, pair, true)
		if err != nil {
			httpError(w, err)
			return
		}
		summaries = append(summaries, PairSummary{
			Pair:         pair,
			LastRealSync: real,
			LastDryRun:   dry,
		})
	}
	writeJSON(w, summaries)
}

func (s *Server) latestIteration(r *http.Request, pair string, dryRun bool) (*Iteration, error) {
	dryVal := 0
	if dryRun {
		dryVal = 1
	}
	row := s.db.QueryRowContext(r.Context(), `
		SELECT id, sync_pair, direction, status, dry_run,
		       started_at, ended_at,
		       files_created, files_updated, files_deleted, files_skipped, files_failed,
		       total_bytes_transferred, error_message
		FROM sync_iterations
		WHERE sync_pair = ? AND dry_run = ?
		ORDER BY started_at DESC
		LIMIT 1`, pair, dryVal)
	return scanIteration(row)
}

func (s *Server) handleIterations(w http.ResponseWriter, r *http.Request) {
	q := r.URL.Query()
	pair := q.Get("pair")
	limit := 20
	if l := q.Get("limit"); l != "" {
		if n, err := strconv.Atoi(l); err == nil && n > 0 {
			limit = n
		}
	}

	var (
		rows *sql.Rows
		err  error
	)

	// dry_run filter (optional)
	dryParam := q.Get("dry_run")

	switch {
	case pair != "" && dryParam != "":
		dryVal, _ := strconv.Atoi(dryParam)
		rows, err = s.db.QueryContext(r.Context(), `
			SELECT id, sync_pair, direction, status, dry_run,
			       started_at, ended_at,
			       files_created, files_updated, files_deleted, files_skipped, files_failed,
			       total_bytes_transferred, error_message
			FROM sync_iterations
			WHERE sync_pair = ? AND dry_run = ?
			ORDER BY started_at DESC
			LIMIT ?`, pair, dryVal, limit)
	case pair != "":
		rows, err = s.db.QueryContext(r.Context(), `
			SELECT id, sync_pair, direction, status, dry_run,
			       started_at, ended_at,
			       files_created, files_updated, files_deleted, files_skipped, files_failed,
			       total_bytes_transferred, error_message
			FROM sync_iterations
			WHERE sync_pair = ?
			ORDER BY started_at DESC
			LIMIT ?`, pair, limit)
	case dryParam != "":
		dryVal, _ := strconv.Atoi(dryParam)
		rows, err = s.db.QueryContext(r.Context(), `
			SELECT id, sync_pair, direction, status, dry_run,
			       started_at, ended_at,
			       files_created, files_updated, files_deleted, files_skipped, files_failed,
			       total_bytes_transferred, error_message
			FROM sync_iterations
			WHERE dry_run = ?
			ORDER BY started_at DESC
			LIMIT ?`, dryVal, limit)
	default:
		rows, err = s.db.QueryContext(r.Context(), `
			SELECT id, sync_pair, direction, status, dry_run,
			       started_at, ended_at,
			       files_created, files_updated, files_deleted, files_skipped, files_failed,
			       total_bytes_transferred, error_message
			FROM sync_iterations
			ORDER BY started_at DESC
			LIMIT ?`, limit)
	}
	if err != nil {
		httpError(w, err)
		return
	}
	defer rows.Close()

	iterations := make([]*Iteration, 0)
	for rows.Next() {
		it, err := scanIterationRow(rows)
		if err != nil {
			httpError(w, err)
			return
		}
		iterations = append(iterations, it)
	}
	if err := rows.Err(); err != nil {
		httpError(w, err)
		return
	}
	writeJSON(w, iterations)
}

func (s *Server) handleOperations(w http.ResponseWriter, r *http.Request) {
	idStr := r.URL.Query().Get("iteration_id")
	if idStr == "" {
		http.Error(w, "iteration_id required", http.StatusBadRequest)
		return
	}
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil {
		http.Error(w, "invalid iteration_id", http.StatusBadRequest)
		return
	}

	rows, err := s.db.QueryContext(r.Context(), `
		SELECT id, iteration_id, dry_run, operation, filepath,
		       size_before, size_after, md5_before, md5_after,
		       started_at, ended_at, status, error_message
		FROM sync_operations
		WHERE iteration_id = ?
		ORDER BY started_at ASC`, id)
	if err != nil {
		httpError(w, err)
		return
	}
	defer rows.Close()

	ops := make([]*Operation, 0)
	for rows.Next() {
		var op Operation
		var dryRun int
		var endedAt sql.NullTime
		var sizeBefore, sizeAfter sql.NullInt64
		var md5Before, md5After, errMsg sql.NullString
		if err := rows.Scan(
			&op.ID, &op.IterationID, &dryRun, &op.Operation, &op.Filepath,
			&sizeBefore, &sizeAfter, &md5Before, &md5After,
			&op.StartedAt, &endedAt, &op.Status, &errMsg,
		); err != nil {
			httpError(w, err)
			return
		}
		op.DryRun = dryRun == 1
		if endedAt.Valid {
			op.EndedAt = &endedAt.Time
		}
		if sizeBefore.Valid {
			op.SizeBefore = &sizeBefore.Int64
		}
		if sizeAfter.Valid {
			op.SizeAfter = &sizeAfter.Int64
		}
		if md5Before.Valid {
			op.Md5Before = &md5Before.String
		}
		if md5After.Valid {
			op.Md5After = &md5After.String
		}
		if errMsg.Valid {
			op.ErrorMessage = &errMsg.String
		}
		ops = append(ops, &op)
	}
	if err := rows.Err(); err != nil {
		httpError(w, err)
		return
	}
	writeJSON(w, ops)
}

// --- helpers ---

func scanIteration(row *sql.Row) (*Iteration, error) {
	var it Iteration
	var dryRun int
	var endedAt sql.NullTime
	var errMsg sql.NullString
	err := row.Scan(
		&it.ID, &it.SyncPair, &it.Direction, &it.Status, &dryRun,
		&it.StartedAt, &endedAt,
		&it.FilesCreated, &it.FilesUpdated, &it.FilesDeleted, &it.FilesSkipped, &it.FilesFailed,
		&it.TotalBytesTransferred, &errMsg,
	)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	it.DryRun = dryRun == 1
	if endedAt.Valid {
		it.EndedAt = &endedAt.Time
	}
	if errMsg.Valid {
		it.ErrorMessage = &errMsg.String
	}
	return &it, nil
}

func scanIterationRow(rows *sql.Rows) (*Iteration, error) {
	var it Iteration
	var dryRun int
	var endedAt sql.NullTime
	var errMsg sql.NullString
	err := rows.Scan(
		&it.ID, &it.SyncPair, &it.Direction, &it.Status, &dryRun,
		&it.StartedAt, &endedAt,
		&it.FilesCreated, &it.FilesUpdated, &it.FilesDeleted, &it.FilesSkipped, &it.FilesFailed,
		&it.TotalBytesTransferred, &errMsg,
	)
	if err != nil {
		return nil, err
	}
	it.DryRun = dryRun == 1
	if endedAt.Valid {
		it.EndedAt = &endedAt.Time
	}
	if errMsg.Valid {
		it.ErrorMessage = &errMsg.String
	}
	return &it, nil
}

func writeJSON(w http.ResponseWriter, v any) {
	w.Header().Set("Content-Type", "application/json")
	if err := json.NewEncoder(w).Encode(v); err != nil {
		http.Error(w, "encode error", http.StatusInternalServerError)
	}
}

func writeError(w http.ResponseWriter, status int, msg string) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	json.NewEncoder(w).Encode(map[string]string{"error": msg})
}

func httpError(w http.ResponseWriter, err error) {
	http.Error(w, err.Error(), http.StatusInternalServerError)
}