package server

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"log/slog"
	"net/http"
	"slices"
	"strconv"
	"strings"
	"time"

	"git.lastassault.de/speatzle/morffix/constants"
	"git.lastassault.de/speatzle/morffix/types"
	"github.com/jackc/pgx/v5"
)

type TasksData struct {
	Libraries      []Library
	FfmpegCommands []FfmpegCommand
	Tasks          []TasksDisplay
	Stats          TaskStats
	OrderBy        string
	OrderAsc       bool
	Limit          uint
	Page           uint
	Count          uint
}

type TaskStats struct {
	RunningCount  int
	QueuedCount   int
	FailedCount   int
	SuccessCount  int
	UnknownCount  int
	AssignedCount int
	PausedCount   int
	WaitingCount  int
	TotalCount    int
}

type TasksDisplay struct {
	ID            int     `db:"id"`
	Library       int     `db:"library"`
	Worker        *string `db:"worker"`
	Type          int     `db:"type"`
	FfmpegCommand *string `db:"ffmpeg_command"`
	Status        string  `db:"status"`
	File          string  `db:"file"`
	UpdatedAt     string  `db:"updated_at"`
}

type TaskDisplay struct {
	ID        int
	Library   string
	Worker    *string
	Type      string
	Status    string
	Filename  string
	Log       []string
	UpdatedAt time.Time
}

type TaskDB struct {
	ID            int                  `db:"id"`
	Library       int                  `db:"library"`
	Worker        *string              `db:"worker"`
	Type          int                  `db:"type"`
	FfmpegCommand *string              `db:"ffmpeg_command"`
	Status        constants.TaskStatus `db:"status"`
	File          string               `db:"file"`
	UpdatedAt     time.Time            `db:"updated_at"`
}

var taskColumns = []string{"id", "library", "worker", "type", "ffmpeg_command", "status", "file", "updated_at"}

func handleTasks(w http.ResponseWriter, r *http.Request) {
	if r.Method == "POST" {
		err := createTask(r.Context(), r)
		if err != nil {
			slog.ErrorContext(r.Context(), "Create Task", "err", err)
			http.Error(w, "Error Create Tasks: "+err.Error(), http.StatusInternalServerError)
			return
		}
	}

	data := TasksData{}

	err := db.QueryRow(r.Context(), `
		SELECT COUNT(*),
		COALESCE(SUM(CASE WHEN status = 0 THEN 1 ELSE 0 END),0),
		COALESCE(SUM(CASE WHEN status = 1 THEN 1 ELSE 0 END),0),
		COALESCE(SUM(CASE WHEN status = 2 THEN 1 ELSE 0 END),0),
		COALESCE(SUM(CASE WHEN status = 3 THEN 1 ELSE 0 END),0),
		COALESCE(SUM(CASE WHEN status = 4 THEN 1 ELSE 0 END),0),
		COALESCE(SUM(CASE WHEN status = 5 THEN 1 ELSE 0 END),0),
		COALESCE(SUM(CASE WHEN status = 6 THEN 1 ELSE 0 END),0),
		COALESCE(SUM(CASE WHEN status = 7 THEN 1 ELSE 0 END),0)
		FROM tasks
	`).Scan(&data.Stats.TotalCount, &data.Stats.UnknownCount, &data.Stats.FailedCount, &data.Stats.SuccessCount, &data.Stats.RunningCount, &data.Stats.QueuedCount, &data.Stats.AssignedCount, &data.Stats.PausedCount, &data.Stats.WaitingCount)
	if err != nil {
		slog.ErrorContext(r.Context(), "Query Task Counts", "err", err)
		http.Error(w, "Error Query Task Counts: "+err.Error(), http.StatusInternalServerError)
		return
	}

	rows, err := db.Query(r.Context(), "SELECT * FROM libraries WHERE enable = $1", true)
	if err != nil {
		slog.ErrorContext(r.Context(), "Query Libraries", "err", err)
		http.Error(w, "Error Query Libraries: "+err.Error(), http.StatusInternalServerError)
		return
	}
	libraries, err := pgx.CollectRows[Library](rows, pgx.RowToStructByName[Library])
	if err != nil {
		slog.ErrorContext(r.Context(), "Collect Rows", "err", err)
		http.Error(w, "Error Collect Libraries: "+err.Error(), http.StatusInternalServerError)
		return
	}
	data.Libraries = libraries

	rows, err = db.Query(r.Context(), "SELECT id, name, data FROM ffmpeg_commands")
	if err != nil {
		slog.ErrorContext(r.Context(), "Query Ffmpeg Commands", "err", err)
		http.Error(w, "Error Ffmpeg Commands: "+err.Error(), http.StatusInternalServerError)
		return
	}
	ffmpegCommands, err := pgx.CollectRows[FfmpegCommand](rows, pgx.RowToStructByName[FfmpegCommand])
	if err != nil {
		slog.ErrorContext(r.Context(), "Collect Ffmpeg Commands", "err", err)
		http.Error(w, "Error Collect Ffmpeg Commands: "+err.Error(), http.StatusInternalServerError)
		return
	}
	data.FfmpegCommands = ffmpegCommands

	query := r.URL.Query()
	data.OrderBy = "updated_at"
	if query.Has(constants.SORT_ORDER_BY_PARAM) {
		if slices.Contains(taskColumns, query.Get(constants.SORT_ORDER_BY_PARAM)) {
			data.OrderBy = query.Get(constants.SORT_ORDER_BY_PARAM)
		} else {
			http.Error(w, "Error Unknown Column in order_by: "+query.Get(constants.SORT_ORDER_BY_PARAM), http.StatusBadRequest)
			return
		}
	}

	orderDir := "DESC"
	if query.Has(constants.SORT_ORDER_ASC_PARAM) {
		orderDir = "ASC"
		data.OrderAsc = true
	}

	data.Limit = 100
	if query.Has(constants.QUERY_LIMIT_PARAM) {
		limit, err := strconv.Atoi(query.Get(constants.QUERY_LIMIT_PARAM))
		if err != nil {
			http.Error(w, "Error Parsing query limit: "+query.Get(constants.QUERY_LIMIT_PARAM), http.StatusBadRequest)
			return
		}
		if limit < 0 {
			http.Error(w, "Error query limit smaller than 0: "+query.Get(constants.QUERY_LIMIT_PARAM), http.StatusBadRequest)
			return
		}
		data.Limit = uint(limit)
	}

	data.Page = 0
	if query.Has(constants.QUERY_PAGE_PARAM) {
		page, err := strconv.Atoi(query.Get(constants.QUERY_PAGE_PARAM))
		if err != nil {
			http.Error(w, "Error Parsing query page: "+query.Get(constants.QUERY_PAGE_PARAM), http.StatusBadRequest)
			return
		}
		if page < 0 {
			http.Error(w, "Error query limit smaller than 0: "+query.Get(constants.QUERY_PAGE_PARAM), http.StatusBadRequest)
			return
		}
		data.Page = uint(page)
	}

	rows, err = db.Query(r.Context(), "SELECT t.id AS id, l.id AS library, w.name AS worker, t.type AS type, fc.name AS ffmpeg_command, t.status AS status, f.path AS file, t.updated_at AS updated_at FROM tasks t INNER JOIN files f ON f.id = t.file_id INNER JOIN libraries l ON l.id = f.library_id INNER JOIN ffmpeg_commands fc ON fc.id = t.ffmpeg_command_id LEFT JOIN workers w ON t.worker_id = w.id "+fmt.Sprintf("ORDER BY %v %v LIMIT %d OFFSET %d", data.OrderBy, orderDir, data.Limit, data.Page*data.Limit))
	if err != nil {
		slog.ErrorContext(r.Context(), "Query Tasks", "err", err)
		http.Error(w, "Error Query Tasks: "+err.Error(), http.StatusInternalServerError)
		return
	}
	tasks, err := pgx.CollectRows[TaskDB](rows, pgx.RowToStructByName[TaskDB])
	if err != nil {
		slog.ErrorContext(r.Context(), "Collect Tasks", "err", err)
		http.Error(w, "Error Query Tasks: "+err.Error(), http.StatusInternalServerError)
		return
	}
	for i := range tasks {
		data.Tasks = append(data.Tasks, TasksDisplay{
			ID:            tasks[i].ID,
			Library:       tasks[i].Library,
			Worker:        tasks[i].Worker,
			Type:          tasks[i].Type,
			FfmpegCommand: tasks[i].FfmpegCommand,
			File:          tasks[i].File,
			Status:        tasks[i].Status.String(),
			UpdatedAt:     tasks[i].UpdatedAt.Format(time.DateTime),
		})
	}
	data.Count = uint(len(tasks))

	buf := bytes.Buffer{}
	err = templates.ExecuteTemplate(&buf, constants.TASKS_TEMPLATE_NAME, data)
	if err != nil {
		slog.ErrorContext(r.Context(), "Executing Task Template", "err", err)
		http.Error(w, "Error Executing Template: "+err.Error(), http.StatusInternalServerError)
		return
	}

	_, err = w.Write(buf.Bytes())
	if err != nil {
		slog.ErrorContext(r.Context(), "Writing http Response", "err", err)
	}
}

func handleTask(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	if id == "" {
		handleTasks(w, r)
		return
	}

	var typ constants.TaskType
	var status constants.TaskStatus
	t := TaskDisplay{}
	err := db.QueryRow(r.Context(), "SELECT t.id, l.name, w.name, t.type, t.status, f.path, t.log, t.updated_at FROM tasks t LEFT JOIN workers w ON w.id = t.worker_id INNER JOIN files f ON f.id = t.file_id INNER JOIN libraries l ON l.id = f.library_id WHERE t.id = $1", id).Scan(&t.ID, &t.Library, &t.Worker, &typ, &status, &t.Filename, &t.Log, &t.UpdatedAt)
	if err != nil {
		slog.ErrorContext(r.Context(), "Query Tasks", "err", err)
		http.Error(w, "Error Query Tasks: "+err.Error(), http.StatusInternalServerError)
		return
	}

	t.Type = typ.String()
	t.Status = status.String()
	buf := bytes.Buffer{}
	err = templates.ExecuteTemplate(&buf, constants.TASK_TEMPLATE_NAME, t)
	if err != nil {
		slog.ErrorContext(r.Context(), "Executing Task Template", "err", err)
		http.Error(w, "Error Executing Template: "+err.Error(), http.StatusInternalServerError)
		return
	}

	_, err = w.Write(buf.Bytes())
	if err != nil {
		slog.ErrorContext(r.Context(), "Writing http Response", "err", err)
	}
}

func createTask(ctx context.Context, r *http.Request) error {
	err := r.ParseForm()
	if err != nil {
		return fmt.Errorf("Parseing Form: %w", err)
	}
	library := r.FormValue("library")
	health := r.FormValue("health")
	transcode := r.FormValue("transcode")
	typ, err := strconv.Atoi(r.FormValue("type"))
	if err != nil {
		return fmt.Errorf("Parsing Task Type: %w", err)
	}
	ffmpeg_command, err := strconv.Atoi(r.FormValue("ffmpeg_command"))
	if err != nil {
		return fmt.Errorf("Parsing FFmpeg Command: %w", err)
	}

	slog.Info("Got Task Create", "library", library, "health", health, "type", typ)

	rows, err := db.Query(r.Context(), "SELECT id, path, size, status, health, transcode, md5, updated_at FROM files where library_id = $1 AND status = $2 AND (-1 = $3 OR health = $3) AND (-1 = $4 OR transcode = $4)", library, constants.FILE_STATUS_EXISTS, health, transcode)
	if err != nil {
		return fmt.Errorf("Query Files: %w", err)
	}
	files, err := pgx.CollectRows[File](rows, pgx.RowToStructByName[File])
	if err != nil {
		return fmt.Errorf("Collect Files: %w", err)
	}

	tx, err := db.Begin(ctx)
	if err != nil {
		return fmt.Errorf("Begin Transaction: %w", err)
	}
	defer tx.Rollback(ctx)

	var data any
	/*
		if typ == constants.TASK_TYPE_HEALTHCHECK {

			// ffmpeg.exe -stats -v error -i "in.mp4" -f null -max_muxing_queue_size 9999 "out.mp4"
			data = types.HealthCheckData{Command: types.FFmpegCommand{
				Args:        []types.Arg{{Flag: "-stats"}, {Flag: "-v", Value: "error"}, {Flag: "-xerror"}},
				InputFiles:  []types.File{{Path: "input.mkv"}},
				OutputFiles: []types.File{{Path: "output.mkv", Arguments: []types.Arg{{Flag: "-f", Value: "null"}, {Flag: "-max_muxing_queue_size", Value: "9999"}}}},
			}}
		} else if typ == constants.TASK_TYPE_TRANSCODE {
			data = types.TranscodeData{Command: types.FFmpegCommand{
				Args:        []types.Arg{{Flag: "-stats"}, {Flag: "-v", Value: "error"}, {Flag: "-xerror"}},
				InputFiles:  []types.File{{Path: "input.mkv"}},
				OutputFiles: []types.File{{Path: "output.mkv", Arguments: []types.Arg{{Flag: "-map", Value: "0"}, {Flag: "-c", Value: "copy"}, {Flag: "-c:a", Value: "aac"}, {Flag: "-c:v", Value: "libsvtav1"}, {Flag: "-crf", Value: "35"}, {Flag: "-preset", Value: "8"}, {Flag: "-max_muxing_queue_size", Value: "9999"}}}},
			}}
		} else {
			return fmt.Errorf("Unkown Task Type: %v", typ)
		}
	*/

	for _, file := range files {
		_, err = db.Exec(r.Context(), "INSERT INTO tasks (file_id, type, status, data, ffmpeg_command_id) VALUES ($1,$2,$3,$4,$5)", file.ID, typ, constants.TASK_STATUS_QUEUED, data, ffmpeg_command)
		if err != nil {
			return fmt.Errorf("Inserting Task: %w", err)
		}
	}

	err = tx.Commit(ctx)
	if err != nil {
		return fmt.Errorf("Committing Transcation: %w", err)
	}

	return nil
}

type QueuedTask struct {
	ID            int
	Type          constants.TaskType
	FileID        int    `json:"file_id"`
	FileMD5       []byte `json:"file_md5" db:"md5"`
	FileExtension string `json:"file_extension"`
	Data          json.RawMessage
	FfmpegCommand types.FFmpegCommand `json:"ffmpeg_command" db:"ffmpeg_command"`
}

var assignRunning = false

func assignQueuedTasks(ctx context.Context) error {
	if assignRunning {
		return nil
	}

	assignRunning = true
	defer func() {
		assignRunning = false
	}()

	rows, err := db.Query(ctx, "SELECT t.id as id, t.type as type, t.file_id as file_id, f.md5 as md5, substring(f.path FROM '\\.([^\\.]*)$') AS file_extension, t.data as data, fc.data as ffmpeg_command FROM tasks t INNER JOIN files f ON f.id = t.file_id INNER JOIN ffmpeg_commands fc ON fc.id = t.ffmpeg_command_id WHERE t.status = $1 AND f.status = $2 ORDER BY type DESC", constants.TASK_STATUS_QUEUED, constants.FILE_STATUS_EXISTS)
	if err != nil {
		return fmt.Errorf("Query Queued Tasks: %w", err)
	}
	queuedTasks, err := pgx.CollectRows[QueuedTask](rows, pgx.RowToStructByName[QueuedTask])
	if err != nil {
		return fmt.Errorf("Collect Queued Tasks: %w", err)
	}

	// TODO, allow overwriting of extension

	//slog.Info("Assigning Queued Tasks", "count", len(queuedTasks))

	if len(queuedTasks) == 0 {
		return nil
	}

	WorkersMutex.Lock()
	defer WorkersMutex.Unlock()

	lastAssigned := 0

	for i := range Workers {
		if lastAssigned == len(queuedTasks) {
			slog.Info("All Tasks assigned")
			// All Tasks have been Assigned
			return nil
		}
		if Workers[i].Connected {
			var queueEnable bool
			var parallelTasks int
			err := db.QueryRow(ctx, "SELECT queue_enable, parallel_tasks FROM workers WHERE id = $1", i).Scan(&queueEnable, &parallelTasks)
			if err != nil {
				return fmt.Errorf("Error Querying Worker Queue Enable: %w", err)
			}
			if !queueEnable {
				slog.DebugContext(ctx, "Skipping Worker since Queueing is disabled", "worker_id", i)
				continue
			}

			var count int
			err = db.QueryRow(ctx, "SELECT COUNT(*) FROM tasks WHERE worker_id = $1 AND (status = $2 OR status = $3 OR status = $4 OR status = $5)", i, constants.TASK_STATUS_UNKNOWN, constants.TASK_STATUS_ASSIGNED, constants.TASK_STATUS_RUNNING, constants.TASK_STATUS_WAITING).Scan(&count)
			if err != nil {
				return fmt.Errorf("Error Querying Worker Task Count: %w", err)
			}

			slog.Debug("Assigning Queued Tasks Worker", "worker", i, "count", count)

			// Allow for Multiple Tasks at once in the future
			if count < parallelTasks {
				tx, err := db.Begin(ctx)
				defer tx.Rollback(ctx)
				if err != nil {
					return fmt.Errorf("Starting Transaction: %w", err)
				}
				_, err = tx.Exec(ctx, "UPDATE tasks SET status = $2, worker_id = $3 WHERE id = $1", queuedTasks[lastAssigned].ID, constants.TASK_STATUS_ASSIGNED, i)
				if err != nil {
					return fmt.Errorf("Setting tasks Assignment: %w", err)
				}

				taskStart := types.TaskStart{
					ID:            queuedTasks[lastAssigned].ID,
					Type:          queuedTasks[lastAssigned].Type,
					FileID:        queuedTasks[lastAssigned].FileID,
					FileMD5:       queuedTasks[lastAssigned].FileMD5,
					FileExtension: queuedTasks[lastAssigned].FileExtension,
					Data:          queuedTasks[lastAssigned].Data,
					FfmpegCommand: queuedTasks[lastAssigned].FfmpegCommand,
				}

				_, err = rpcServer.Call(ctx, Workers[i].Conn, "task-start", taskStart, nil)
				if err != nil {
					if strings.HasSuffix(err.Error(), constants.ErrTaskIsAlreadyRunning.Error()) {
						// Task was started previously but something went wrong and we are out of sync
						slog.WarnContext(ctx, "Task is apparently already Running on this Worker, thats bad", "task_id", taskStart.ID, "worker", Workers[i].Name)

						_, err = tx.Exec(ctx, "UPDATE tasks SET status = $2, log = log || $3 WHERE id = $1", taskStart.ID, constants.TASK_STATUS_ASSIGNED, []string{fmt.Sprintf("%v MASTER: Task Start, Task Already Running!", time.Now())})
						if err != nil {
							return fmt.Errorf("Updating Task status during already running error: %w", err)
						}
					} else if errors.Is(err, constants.ErrRPCRequestTimeout) {
						// We really don't know whats going on, might be slow response, oom, disk full or a bug
						slog.WarnContext(ctx, "Task start Timed Out", "task_id", taskStart.ID, "worker", Workers[i].Name)

						_, err = tx.Exec(ctx, "UPDATE tasks SET status = $2, log = log || $3 WHERE id = $1", taskStart.ID, constants.TASK_STATUS_UNKNOWN, []string{fmt.Sprintf("%v MASTER: Task Start RPC Call Timed Out!", time.Now())})
						if err != nil {
							return fmt.Errorf("Updating Unknown Task Status due to Timeout while starting Task: %w", err)
						}
					} else {
						slog.ErrorContext(ctx, "Task start Error", "task_id", taskStart.ID, "worker", Workers[i].Name)

						_, err = tx.Exec(ctx, "UPDATE tasks SET status = $2, log = log || $3 WHERE id = $1", taskStart.ID, constants.TASK_STATUS_UNKNOWN, []string{fmt.Sprintf("%v MASTER: Task Start Error: %v", time.Now(), err.Error())})
						if err != nil {
							return fmt.Errorf("Updating Unknown Task Status due to Error while starting Task: %w", err)
						}
					}
				}

				err = tx.Commit(ctx)
				if err != nil {
					return fmt.Errorf("Error Committing Transaction: %w", err)
				}

				slog.InfoContext(ctx, "Assigned Task to Worker", "task", queuedTasks[lastAssigned].ID, "worker", i)
				lastAssigned++
			}
		}
	}
	return nil
}