package daemon

import (
	"context"
	"fmt"
	"strings"
	"sync"
	"time"

	"banger/internal/api"
	"banger/internal/model"
)

func (op *imageBuildOperationState) ID() string           { return op.snapshot().ID }
func (op *imageBuildOperationState) IsDone() bool         { return op.snapshot().Done }
func (op *imageBuildOperationState) UpdatedAt() time.Time { return op.snapshot().UpdatedAt }
func (op *imageBuildOperationState) Cancel()              { op.cancelOperation() }

type imageBuildProgressKey struct{}

type imageBuildOperationState struct {
	mu     sync.Mutex
	cancel context.CancelFunc
	op     api.ImageBuildOperation
}

func newImageBuildOperationState() (*imageBuildOperationState, error) {
	id, err := model.NewID()
	if err != nil {
		return nil, err
	}
	now := model.Now()
	return &imageBuildOperationState{
		op: api.ImageBuildOperation{
			ID:        id,
			Stage:     "queued",
			Detail:    "waiting to start",
			StartedAt: now,
			UpdatedAt: now,
		},
	}, nil
}

func withImageBuildProgress(ctx context.Context, op *imageBuildOperationState) context.Context {
	if op == nil {
		return ctx
	}
	return context.WithValue(ctx, imageBuildProgressKey{}, op)
}

func imageBuildProgressFromContext(ctx context.Context) *imageBuildOperationState {
	if ctx == nil {
		return nil
	}
	op, _ := ctx.Value(imageBuildProgressKey{}).(*imageBuildOperationState)
	return op
}

func imageBuildStage(ctx context.Context, stage, detail string) {
	if op := imageBuildProgressFromContext(ctx); op != nil {
		op.stage(stage, detail)
	}
}

func imageBuildBindImage(ctx context.Context, image model.Image) {
	if op := imageBuildProgressFromContext(ctx); op != nil {
		op.bindImage(image)
	}
}

func imageBuildSetLogPath(ctx context.Context, path string) {
	if op := imageBuildProgressFromContext(ctx); op != nil {
		op.setLogPath(path)
	}
}

func (op *imageBuildOperationState) setCancel(cancel context.CancelFunc) {
	op.mu.Lock()
	defer op.mu.Unlock()
	op.cancel = cancel
}

func (op *imageBuildOperationState) setLogPath(path string) {
	op.mu.Lock()
	defer op.mu.Unlock()
	op.op.BuildLogPath = strings.TrimSpace(path)
	op.op.UpdatedAt = model.Now()
}

func (op *imageBuildOperationState) bindImage(image model.Image) {
	op.mu.Lock()
	defer op.mu.Unlock()
	op.op.ImageID = image.ID
	op.op.ImageName = image.Name
}

func (op *imageBuildOperationState) stage(stage, detail string) {
	op.mu.Lock()
	defer op.mu.Unlock()
	stage = strings.TrimSpace(stage)
	detail = strings.TrimSpace(detail)
	if stage == "" {
		stage = op.op.Stage
	}
	if stage == op.op.Stage && detail == op.op.Detail {
		return
	}
	op.op.Stage = stage
	op.op.Detail = detail
	op.op.UpdatedAt = model.Now()
}

func (op *imageBuildOperationState) done(image model.Image) {
	op.mu.Lock()
	defer op.mu.Unlock()
	imageCopy := image
	op.op.ImageID = image.ID
	op.op.ImageName = image.Name
	op.op.Stage = "ready"
	op.op.Detail = "image is ready"
	op.op.Done = true
	op.op.Success = true
	op.op.Error = ""
	op.op.Image = &imageCopy
	op.op.UpdatedAt = model.Now()
}

func (op *imageBuildOperationState) fail(err error) {
	op.mu.Lock()
	defer op.mu.Unlock()
	op.op.Done = true
	op.op.Success = false
	if err != nil {
		op.op.Error = err.Error()
	}
	if strings.TrimSpace(op.op.Detail) == "" {
		op.op.Detail = "image build failed"
	}
	op.op.UpdatedAt = model.Now()
}

func (op *imageBuildOperationState) snapshot() api.ImageBuildOperation {
	op.mu.Lock()
	defer op.mu.Unlock()
	snapshot := op.op
	if snapshot.Image != nil {
		imageCopy := *snapshot.Image
		snapshot.Image = &imageCopy
	}
	return snapshot
}

func (op *imageBuildOperationState) cancelOperation() {
	op.mu.Lock()
	cancel := op.cancel
	op.mu.Unlock()
	if cancel != nil {
		cancel()
	}
}

func (d *Daemon) BeginImageBuild(_ context.Context, params api.ImageBuildParams) (api.ImageBuildOperation, error) {
	op, err := newImageBuildOperationState()
	if err != nil {
		return api.ImageBuildOperation{}, err
	}
	buildCtx, cancel := context.WithCancel(context.Background())
	op.setCancel(cancel)
	d.imageBuildOps.Insert(op)
	go d.runImageBuildOperation(withImageBuildProgress(buildCtx, op), op, params)
	return op.snapshot(), nil
}

func (d *Daemon) runImageBuildOperation(ctx context.Context, op *imageBuildOperationState, params api.ImageBuildParams) {
	image, err := d.BuildImage(ctx, params)
	if err != nil {
		op.fail(err)
		return
	}
	op.done(image)
}

func (d *Daemon) ImageBuildStatus(_ context.Context, id string) (api.ImageBuildOperation, error) {
	op, ok := d.imageBuildOps.Get(strings.TrimSpace(id))
	if !ok {
		return api.ImageBuildOperation{}, fmt.Errorf("image build operation not found: %s", id)
	}
	return op.snapshot(), nil
}

func (d *Daemon) CancelImageBuild(_ context.Context, id string) error {
	op, ok := d.imageBuildOps.Get(strings.TrimSpace(id))
	if !ok {
		return fmt.Errorf("image build operation not found: %s", id)
	}
	op.cancelOperation()
	return nil
}

func (d *Daemon) pruneImageBuildOperations(olderThan time.Time) {
	d.imageBuildOps.Prune(olderThan)
}