package executor

import (
	"testing"

	"github.com/go-kit/log"
	"github.com/stretchr/testify/require"

	"github.com/grafana/loki/v3/pkg/engine/internal/planner/physical"
)

func TestExecutor(t *testing.T) {
	t.Run("pipeline fails if plan is nil", func(t *testing.T) {
		ctx := t.Context()
		pipeline := Run(ctx, Config{}, nil, log.NewNopLogger())
		_, err := pipeline.Read(ctx)
		require.ErrorContains(t, err, "failed to execute pipeline: plan is nil")
	})

	t.Run("pipeline fails if plan has no root node", func(t *testing.T) {
		ctx := t.Context()
		pipeline := Run(ctx, Config{}, &physical.Plan{}, log.NewNopLogger())
		_, err := pipeline.Read(ctx)
		require.ErrorContains(t, err, "failed to execute pipeline: plan has no root node")
	})
}

func TestExecutor_Limit(t *testing.T) {
	t.Run("no inputs result in empty pipeline", func(t *testing.T) {
		ctx := t.Context()
		c := &Context{}
		pipeline := c.executeLimit(ctx, &physical.Limit{}, nil, nil)
		_, err := pipeline.Read(ctx)
		require.ErrorContains(t, err, EOF.Error())
	})

	t.Run("multiple inputs result in error", func(t *testing.T) {
		ctx := t.Context()
		c := &Context{}
		pipeline := c.executeLimit(ctx, &physical.Limit{}, []Pipeline{emptyPipeline(), emptyPipeline()}, nil)
		_, err := pipeline.Read(ctx)
		require.ErrorContains(t, err, "limit expects exactly one input, got 2")
	})
}

func TestExecutor_Filter(t *testing.T) {
	t.Run("no inputs result in empty pipeline", func(t *testing.T) {
		ctx := t.Context()
		c := &Context{}
		pipeline := c.executeFilter(ctx, &physical.Filter{}, nil, nil)
		_, err := pipeline.Read(ctx)
		require.ErrorContains(t, err, EOF.Error())
	})

	t.Run("multiple inputs result in error", func(t *testing.T) {
		ctx := t.Context()
		c := &Context{}
		pipeline := c.executeFilter(ctx, &physical.Filter{}, []Pipeline{emptyPipeline(), emptyPipeline()}, nil)
		_, err := pipeline.Read(ctx)
		require.ErrorContains(t, err, "filter expects exactly one input, got 2")
	})
}

func TestExecutor_Projection(t *testing.T) {
	t.Run("no inputs result in empty pipeline", func(t *testing.T) {
		ctx := t.Context()
		c := &Context{}
		pipeline := c.executeProjection(ctx, &physical.Projection{}, nil, nil)
		_, err := pipeline.Read(ctx)
		require.ErrorContains(t, err, EOF.Error())
	})

	t.Run("missing column expression results in error", func(t *testing.T) {
		ctx := t.Context()
		cols := []physical.Expression{}
		c := &Context{}
		pipeline := c.executeProjection(ctx, &physical.Projection{Expressions: cols}, []Pipeline{emptyPipeline()}, nil)
		_, err := pipeline.Read(ctx)
		require.ErrorContains(t, err, "projection expects at least one expression, got 0")
	})

	t.Run("multiple inputs result in error", func(t *testing.T) {
		ctx := t.Context()
		c := &Context{}
		pipeline := c.executeProjection(ctx, &physical.Projection{}, []Pipeline{emptyPipeline(), emptyPipeline()}, nil)
		_, err := pipeline.Read(ctx)
		require.ErrorContains(t, err, "projection expects exactly one input, got 2")
	})
}