package api

import (
	"bufio"
	"encoding/json"
	"errors"
	"fmt"
	"log/slog"
	"net/http"
	"strings"

	"github.com/go-chi/chi/v5"

	"github.com/alexei/tinyforge/internal/store"
)

// listProjectImages handles GET /api/projects/{id}/images.
// Returns all local Docker images matching the project's image reference.
func (s *Server) listProjectImages(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")

	project, err := s.store.GetProjectByID(id)
	if err != nil {
		if errors.Is(err, store.ErrNotFound) {
			respondNotFound(w, "project")
			return
		}
		slog.Error("failed to get project", "error", err)
		respondError(w, http.StatusInternalServerError, "internal server error")
		return
	}

	if s.docker == nil || project.Image == "" {
		respondJSON(w, http.StatusOK, []any{})
		return
	}

	images, err := s.docker.ListImagesByRef(r.Context(), project.Image)
	if err != nil {
		slog.Warn("list project images", "project", project.Name, "error", err)
		respondJSON(w, http.StatusOK, []any{})
		return
	}

	respondJSON(w, http.StatusOK, images)
}

// streamContainerLogs handles GET /api/projects/{id}/stages/{stage}/instances/{iid}/logs.
// Streams container logs via SSE. Supports query params:
// - tail: number of lines from end (default "200")
// - follow: "true" to stream new lines in real-time
func (s *Server) streamContainerLogs(w http.ResponseWriter, r *http.Request) {
	instanceID := chi.URLParam(r, "iid")

	inst, err := s.store.GetInstanceByID(instanceID)
	if err != nil {
		if errors.Is(err, store.ErrNotFound) {
			respondNotFound(w, "instance")
			return
		}
		slog.Error("failed to get instance", "error", err)
		respondError(w, http.StatusInternalServerError, "internal server error")
		return
	}

	if inst.ContainerID == "" {
		respondError(w, http.StatusBadRequest, "instance has no container")
		return
	}

	if s.docker == nil {
		respondError(w, http.StatusServiceUnavailable, "Docker is not available")
		return
	}

	tail := r.URL.Query().Get("tail")
	if tail == "" {
		tail = "200"
	}
	follow := r.URL.Query().Get("follow") == "true"

	// Check if client accepts SSE.
	accept := r.Header.Get("Accept")
	isSSE := strings.Contains(accept, "text/event-stream")

	logReader, err := s.docker.ContainerLogs(r.Context(), inst.ContainerID, follow && isSSE, tail)
	if err != nil {
		slog.Error("failed to get container logs", "instance", instanceID, "error", err)
		respondError(w, http.StatusInternalServerError, "failed to get container logs")
		return
	}
	defer logReader.Close()

	if !isSSE {
		// JSON mode: read all lines and return as array.
		scanner := bufio.NewScanner(logReader)
		var lines []string
		for scanner.Scan() {
			line := sanitizeDockerLogLine(scanner.Text())
			if line != "" {
				lines = append(lines, line)
			}
		}
		if lines == nil {
			lines = []string{}
		}
		respondJSON(w, http.StatusOK, lines)
		return
	}

	// SSE mode: stream lines as they arrive.
	flusher, ok := w.(http.Flusher)
	if !ok {
		respondError(w, http.StatusInternalServerError, "streaming not supported")
		return
	}

	w.Header().Set("Content-Type", "text/event-stream")
	w.Header().Set("Cache-Control", "no-cache")
	w.Header().Set("Connection", "keep-alive")

	scanner := bufio.NewScanner(logReader)
	for scanner.Scan() {
		line := sanitizeDockerLogLine(scanner.Text())
		if line == "" {
			continue
		}

		data, _ := json.Marshal(map[string]string{"line": line})
		fmt.Fprintf(w, "data: %s\n\n", data)
		flusher.Flush()

		// Check if client disconnected.
		select {
		case <-r.Context().Done():
			return
		default:
		}
	}
}

// sanitizeDockerLogLine strips the Docker log stream header (8-byte prefix)
// that Docker adds to non-TTY container logs.
func sanitizeDockerLogLine(line string) string {
	// Docker multiplexed stream: first 8 bytes are header (stream type + size).
	// If the line starts with a non-printable byte followed by 0x00 0x00 0x00, strip 8 bytes.
	if len(line) > 8 && (line[0] == 1 || line[0] == 2) && line[1] == 0 && line[2] == 0 && line[3] == 0 {
		return line[8:]
	}
	return line
}

// unusedImageStats handles GET /api/docker/unused-images.
// Returns the total size of unused project images and whether the threshold is exceeded.
func (s *Server) unusedImageStats(w http.ResponseWriter, r *http.Request) {
	if s.docker == nil {
		respondJSON(w, http.StatusOK, map[string]any{
			"total_size_mb": 0, "count": 0, "threshold_mb": 0, "exceeded": false,
		})
		return
	}

	settings, err := s.store.GetSettings()
	if err != nil {
		slog.Error("unused images: get settings", "error", err)
		respondError(w, http.StatusInternalServerError, "internal server error")
		return
	}

	projects, err := s.store.GetAllProjects()
	if err != nil {
		slog.Error("unused images: list projects", "error", err)
		respondError(w, http.StatusInternalServerError, "internal server error")
		return
	}

	// Build set of active image refs.
	activeImages := make(map[string]bool)
	for _, p := range projects {
		stages, _ := s.store.GetStagesByProjectID(p.ID)
		for _, st := range stages {
			instances, _ := s.store.GetInstancesByStageID(st.ID)
			for _, inst := range instances {
				if inst.ImageTag != "" {
					activeImages[p.Image+":"+inst.ImageTag] = true
				}
			}
		}
	}

	// Sum unused image sizes.
	ctx := r.Context()
	var totalSize int64
	var count int
	for _, p := range projects {
		if p.Image == "" {
			continue
		}
		images, err := s.docker.ListImagesByRef(ctx, p.Image)
		if err != nil {
			continue
		}
		for _, img := range images {
			if !activeImages[img.Ref] {
				totalSize += img.Size
				count++
			}
		}
	}

	totalMB := totalSize / (1024 * 1024)
	exceeded := settings.ImagePruneThresholdMB > 0 && int(totalMB) >= settings.ImagePruneThresholdMB

	respondJSON(w, http.StatusOK, map[string]any{
		"total_size_mb": totalMB,
		"count":         count,
		"threshold_mb":  settings.ImagePruneThresholdMB,
		"exceeded":      exceeded,
	})
}

// pruneImages handles POST /api/docker/prune-images.
// Only removes images that belong to Tinyforge projects (not all system images).
func (s *Server) pruneImages(w http.ResponseWriter, r *http.Request) {
	if s.docker == nil {
		respondError(w, http.StatusServiceUnavailable, "Docker is not available")
		return
	}

	// Collect all image references from our projects.
	projects, err := s.store.GetAllProjects()
	if err != nil {
		slog.Error("prune: failed to list projects", "error", err)
		respondError(w, http.StatusInternalServerError, "internal server error")
		return
	}

	// Build a set of image refs used by active instances.
	activeImages := make(map[string]bool)
	for _, p := range projects {
		stages, _ := s.store.GetStagesByProjectID(p.ID)
		for _, st := range stages {
			instances, _ := s.store.GetInstancesByStageID(st.ID)
			for _, inst := range instances {
				if inst.ImageTag != "" {
					activeImages[p.Image+":"+inst.ImageTag] = true
				}
			}
		}
	}

	// Collect all unique image bases from projects (without tags).
	projectImages := make(map[string]bool)
	for _, p := range projects {
		if p.Image != "" {
			projectImages[p.Image] = true
		}
	}

	if len(projectImages) == 0 {
		respondJSON(w, http.StatusOK, map[string]any{
			"images_removed":     0,
			"space_reclaimed_mb": 0,
			"message":            "No project images to clean up",
		})
		return
	}

	// List all local Docker images and find ones matching our projects but not actively used.
	ctx := r.Context()
	removed := 0
	var reclaimedBytes int64

	for imageBase := range projectImages {
		// List all tags for this image.
		images, err := s.docker.ListImagesByRef(ctx, imageBase)
		if err != nil {
			slog.Warn("prune: list images", "image", imageBase, "error", err)
			continue
		}

		for _, img := range images {
			// Skip images that are actively used by running instances.
			if activeImages[img.Ref] {
				continue
			}

			// Remove unused image.
			if err := s.docker.RemoveImage(ctx, img.ID); err != nil {
				slog.Warn("prune: remove image", "image", img.Ref, "error", err)
				continue
			}
			removed++
			reclaimedBytes += img.Size
			slog.Info("prune: removed image", "ref", img.Ref, "size_mb", img.Size/(1024*1024))
		}
	}

	respondJSON(w, http.StatusOK, map[string]any{
		"images_removed":     removed,
		"space_reclaimed_mb": reclaimedBytes / (1024 * 1024),
	})
}