// Package teststore provides a common.Storage implementation for testing/mocking purposes.
//
// A new teststore.TestStore can be obtained with teststore.New. Whenever one of the common.Storage
// methods is called, the implementation selects what function to call in the following order:
//  1. If an override for that method was provided at construction time (via teststore.WithXXX()) or
//     afterwards via SetOption, that override is used.
//  2. If a substorage was provided at construction time (via teststore.WithSubstorage()) or afterwars
//     via SetOption, the corresponding method in the substorage is used.
//  3. If none of the above apply, the call panics with an error describing the unexpected call.
//
// It's safe to call SetOption and the overrides from multiple goroutines, but it's the override's
// responsibility to ensure safety of whatever operation it executes.
package teststore

import (
	"context"
	"errors"
	"fmt"
	"sync"

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/compression"
)

// TestStore is a common.Storage implementation for testing/mocking purposes.
type TestStore struct {
	mu sync.RWMutex
	*cfg
}

// ErrDiskExploded is a phony error which can be used for testing purposes to differentiate it from
// more common errors.
var ErrDiskExploded = errors.New("disk exploded")

// New returns a teststore.TestStore from the given options.
func New(opts ...Option) *TestStore {
	c := &cfg{}
	for _, opt := range opts {
		opt(c)
	}
	return &TestStore{cfg: c}
}

// SetOption overrides an option of an existing teststore.TestStore.
// This is useful for overriding methods during a test so that different
// behaviors are simulated.
func (s *TestStore) SetOption(opt Option) {
	s.mu.Lock()
	defer s.mu.Unlock()
	opt(s.cfg)
}

func (s *TestStore) Open(readOnly bool) error {
	s.mu.RLock()
	defer s.mu.RUnlock()
	switch {
	case s.overrides.Open != nil:
		return s.overrides.Open(readOnly)
	case s.st != nil:
		return s.st.Open(readOnly)
	default:
		panic(fmt.Sprintf("unexpected storage call: Open(%v)", readOnly))
	}
}

func (s *TestStore) Init() error {
	s.mu.RLock()
	defer s.mu.RUnlock()
	switch {
	case s.overrides.Init != nil:
		return s.overrides.Init()
	case s.st != nil:
		return s.st.Init()
	default:
		panic("unexpected storage call: Init()")
	}
}

func (s *TestStore) Close() error {
	s.mu.RLock()
	defer s.mu.RUnlock()
	switch {
	case s.overrides.Close != nil:
		return s.overrides.Close()
	case s.st != nil:
		return s.st.Close()
	default:
		panic("unexpected storage call: Close()")
	}
}

func (s *TestStore) Type() string {
	s.mu.RLock()
	defer s.mu.RUnlock()
	switch {
	case s.overrides.Type != nil:
		return s.overrides.Type()
	case s.st != nil:
		return s.st.Type()
	default:
		panic("unexpected storage call: Type()")
	}
}

func (s *TestStore) Path() string {
	s.mu.RLock()
	defer s.mu.RUnlock()
	switch {
	case s.overrides.Path != nil:
		return s.overrides.Path()
	case s.st != nil:
		return s.st.Path()
	default:
		panic("unexpected storage call: Path()")
	}
}

func (s *TestStore) SetCompressor(cc *compression.Config) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	switch {
	case s.overrides.SetCompressor != nil:
		s.overrides.SetCompressor(cc)
	case s.st != nil:
		s.st.SetCompressor(cc)
	default:
		panic(fmt.Sprintf("unexpected storage call: SetCompressor(%+v)", cc))
	}
}

func (s *TestStore) Compressor() *compression.Config {
	s.mu.RLock()
	defer s.mu.RUnlock()
	switch {
	case s.overrides.Compressor != nil:
		return s.overrides.Compressor()
	case s.st != nil:
		return s.st.Compressor()
	default:
		panic("unexpected storage call: Compressor()")
	}
}

func (s *TestStore) SetReportErrorFunc(f func(string, error)) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	switch {
	case s.overrides.SetReportErrorFunc != nil:
		s.overrides.SetReportErrorFunc(f)
	case s.st != nil:
		s.st.SetReportErrorFunc(f)
	default:
		panic("unexpected storage call: SetReportErrorFunc(<func>)")
	}
}

func (s *TestStore) Get(ctx context.Context, req common.GetPrm) (common.GetRes, error) {
	switch {
	case s.overrides.Get != nil:
		return s.overrides.Get(req)
	case s.st != nil:
		return s.st.Get(ctx, req)
	default:
		panic(fmt.Sprintf("unexpected storage call: Get(%+v)", req))
	}
}

func (s *TestStore) GetRange(ctx context.Context, req common.GetRangePrm) (common.GetRangeRes, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	switch {
	case s.overrides.GetRange != nil:
		return s.overrides.GetRange(req)
	case s.st != nil:
		return s.st.GetRange(ctx, req)
	default:
		panic(fmt.Sprintf("unexpected storage call: GetRange(%+v)", req))
	}
}

func (s *TestStore) Exists(ctx context.Context, req common.ExistsPrm) (common.ExistsRes, error) {
	switch {
	case s.overrides.Exists != nil:
		return s.overrides.Exists(req)
	case s.st != nil:
		return s.st.Exists(ctx, req)
	default:
		panic(fmt.Sprintf("unexpected storage call: Exists(%+v)", req))
	}
}

func (s *TestStore) Put(ctx context.Context, req common.PutPrm) (common.PutRes, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	switch {
	case s.overrides.Put != nil:
		return s.overrides.Put(req)
	case s.st != nil:
		return s.st.Put(ctx, req)
	default:
		panic(fmt.Sprintf("unexpected storage call: Put(%+v)", req))
	}
}

func (s *TestStore) Delete(ctx context.Context, req common.DeletePrm) (common.DeleteRes, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	switch {
	case s.overrides.Delete != nil:
		return s.overrides.Delete(req)
	case s.st != nil:
		return s.st.Delete(ctx, req)
	default:
		panic(fmt.Sprintf("unexpected storage call: Delete(%+v)", req))
	}
}

func (s *TestStore) Iterate(ctx context.Context, req common.IteratePrm) (common.IterateRes, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	switch {
	case s.overrides.Iterate != nil:
		return s.overrides.Iterate(req)
	case s.st != nil:
		return s.st.Iterate(ctx, req)
	default:
		panic(fmt.Sprintf("unexpected storage call: Iterate(%+v)", req))
	}
}

func (s *TestStore) SetParentID(string) {}

func (s *TestStore) Rebuild(_ context.Context, _ common.RebuildPrm) (common.RebuildRes, error) {
	return common.RebuildRes{}, nil
}