package api_test

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"io"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"github.com/docker/docker/api/types"
	"github.com/shcizo/package-updater/internal/api"
	"github.com/shcizo/package-updater/internal/discovery"
	"github.com/shcizo/package-updater/internal/updater"
	"github.com/stretchr/testify/require"
)

type fakeFinder struct {
	jobs []discovery.Job
	err  error

	// gotImage records the image argument passed to FindJobs, for
	// assertions on the exact reference the handler built.
	gotImage string
	// swarmShaped, when true, makes FindJobs return a Job whose Image
	// field carries the received image argument, simulating
	// discovery.SwarmDiscovery.FindJobs.
	swarmShaped bool
}

func (f *fakeFinder) FindJobs(_ context.Context, image string) ([]discovery.Job, error) {
	f.gotImage = image
	if f.swarmShaped {
		return []discovery.Job{{Service: "myapp_web", ServiceID: "svc1", Image: image}}, f.err
	}
	return f.jobs, f.err
}

type fakeSubmitter struct {
	results []updater.Result
}

func (f *fakeSubmitter) Submit(_ context.Context, jobs []discovery.Job) []updater.Result {
	if f.results != nil {
		return f.results
	}
	out := make([]updater.Result, len(jobs))
	for i, j := range jobs {
		out[i] = updater.Result{Job: j, Status: updater.StatusUpdated}
	}
	return out
}

type fakePinger struct{ err error }

func (f *fakePinger) Ping(_ context.Context) (types.Ping, error) {
	return types.Ping{}, f.err
}

func decode[T any](t *testing.T, body io.Reader) T {
	t.Helper()
	var v T
	require.NoError(t, json.NewDecoder(body).Decode(&v))
	return v
}

func TestUpdate_ValidationError(t *testing.T) {
	h := api.NewHandlers(&fakeFinder{}, &fakeSubmitter{}, &fakePinger{}, "v0.0.0", "abc", "now", nil)
	req := httptest.NewRequest(http.MethodPost, "/update",
		strings.NewReader(`{"tag":"v1.2.3"}`))
	w := httptest.NewRecorder()
	h.Update(w, req)
	require.Equal(t, http.StatusBadRequest, w.Code)
}

func TestUpdate_BadJSON(t *testing.T) {
	h := api.NewHandlers(&fakeFinder{}, &fakeSubmitter{}, &fakePinger{}, "v0.0.0", "abc", "now", nil)
	req := httptest.NewRequest(http.MethodPost, "/update", strings.NewReader(`not json`))
	w := httptest.NewRecorder()
	h.Update(w, req)
	require.Equal(t, http.StatusBadRequest, w.Code)
}

func TestUpdate_DiscoveryFailureReturns500(t *testing.T) {
	finder := &fakeFinder{err: errors.New("daemon unreachable")}
	h := api.NewHandlers(finder, &fakeSubmitter{}, &fakePinger{}, "v0.0.0", "abc", "now", nil)
	body, _ := json.Marshal(api.UpdateRequest{Image: "r/x"})
	req := httptest.NewRequest(http.MethodPost, "/update", bytes.NewReader(body))
	w := httptest.NewRecorder()
	h.Update(w, req)
	require.Equal(t, http.StatusInternalServerError, w.Code)
}

func TestUpdate_ZeroMatchesReturns200(t *testing.T) {
	h := api.NewHandlers(&fakeFinder{}, &fakeSubmitter{}, &fakePinger{}, "v0.0.0", "abc", "now", nil)
	body, _ := json.Marshal(api.UpdateRequest{Image: "r/x"})
	req := httptest.NewRequest(http.MethodPost, "/update", bytes.NewReader(body))
	w := httptest.NewRecorder()
	h.Update(w, req)
	require.Equal(t, http.StatusOK, w.Code)
	resp := decode[api.UpdateResponse](t, w.Body)
	require.Equal(t, 0, resp.Matched)
}

func TestUpdate_AllSucceeded200(t *testing.T) {
	finder := &fakeFinder{jobs: []discovery.Job{
		{Project: "p", Service: "s", WorkingDir: "/x", ConfigFiles: []string{"/x/c.yml"}},
	}}
	h := api.NewHandlers(finder, &fakeSubmitter{}, &fakePinger{}, "v0.0.0", "abc", "now", nil)
	body, _ := json.Marshal(api.UpdateRequest{Image: "r/x", Tag: "v1"})
	req := httptest.NewRequest(http.MethodPost, "/update", bytes.NewReader(body))
	w := httptest.NewRecorder()
	h.Update(w, req)
	require.Equal(t, http.StatusOK, w.Code)
	resp := decode[api.UpdateResponse](t, w.Body)
	require.Equal(t, 1, resp.Matched)
	require.Equal(t, "updated", resp.Results[0].Status)
	require.Equal(t, "/x/c.yml", resp.Results[0].ComposeFile)
}

func TestUpdate_MixedReturns207(t *testing.T) {
	jobs := []discovery.Job{
		{Project: "p1", Service: "s", ConfigFiles: []string{"/x/c.yml"}},
		{Project: "p2", Service: "s", ConfigFiles: []string{"/y/c.yml"}},
	}
	finder := &fakeFinder{jobs: jobs}
	submitter := &fakeSubmitter{results: []updater.Result{
		{Job: jobs[0], Status: updater.StatusUpdated},
		{Job: jobs[1], Status: updater.StatusFailed, Error: "boom"},
	}}
	h := api.NewHandlers(finder, submitter, &fakePinger{}, "v0.0.0", "abc", "now", nil)
	body, _ := json.Marshal(api.UpdateRequest{Image: "r/x"})
	req := httptest.NewRequest(http.MethodPost, "/update", bytes.NewReader(body))
	w := httptest.NewRecorder()
	h.Update(w, req)
	require.Equal(t, http.StatusMultiStatus, w.Code)
}

func TestUpdate_AllFailedReturns500(t *testing.T) {
	jobs := []discovery.Job{{Project: "p", Service: "s", ConfigFiles: []string{"/x/c.yml"}}}
	finder := &fakeFinder{jobs: jobs}
	submitter := &fakeSubmitter{results: []updater.Result{
		{Job: jobs[0], Status: updater.StatusFailed, Error: "boom"},
	}}
	h := api.NewHandlers(finder, submitter, &fakePinger{}, "v0.0.0", "abc", "now", nil)
	body, _ := json.Marshal(api.UpdateRequest{Image: "r/x"})
	req := httptest.NewRequest(http.MethodPost, "/update", bytes.NewReader(body))
	w := httptest.NewRecorder()
	h.Update(w, req)
	require.Equal(t, http.StatusInternalServerError, w.Code)
}

func TestHealthz_OKWhenDockerUp(t *testing.T) {
	h := api.NewHandlers(&fakeFinder{}, &fakeSubmitter{}, &fakePinger{}, "v0.0.0", "abc", "now", nil)
	req := httptest.NewRequest(http.MethodGet, "/healthz", nil)
	w := httptest.NewRecorder()
	h.Healthz(w, req)
	require.Equal(t, http.StatusOK, w.Code)
}

func TestHealthz_503WhenDockerDown(t *testing.T) {
	h := api.NewHandlers(&fakeFinder{}, &fakeSubmitter{}, &fakePinger{err: errors.New("ping fail")}, "v0.0.0", "abc", "now", nil)
	req := httptest.NewRequest(http.MethodGet, "/healthz", nil)
	w := httptest.NewRecorder()
	h.Healthz(w, req)
	require.Equal(t, http.StatusServiceUnavailable, w.Code)
}

func TestUpdate_FindJobsCalledWithTaggedImage(t *testing.T) {
	finder := &fakeFinder{}
	h := api.NewHandlers(finder, &fakeSubmitter{}, &fakePinger{}, "v0.0.0", "abc", "now", nil)
	body, _ := json.Marshal(api.UpdateRequest{Image: "registry.example.com/myapp", Tag: "v2"})
	req := httptest.NewRequest(http.MethodPost, "/update", bytes.NewReader(body))
	w := httptest.NewRecorder()
	h.Update(w, req)
	require.Equal(t, "registry.example.com/myapp:v2", finder.gotImage)
}

func TestUpdate_FindJobsCalledWithBareImageWhenNoTag(t *testing.T) {
	finder := &fakeFinder{}
	h := api.NewHandlers(finder, &fakeSubmitter{}, &fakePinger{}, "v0.0.0", "abc", "now", nil)
	body, _ := json.Marshal(api.UpdateRequest{Image: "registry.example.com/myapp"})
	req := httptest.NewRequest(http.MethodPost, "/update", bytes.NewReader(body))
	w := httptest.NewRecorder()
	h.Update(w, req)
	require.Equal(t, "registry.example.com/myapp", finder.gotImage)
}

func TestUpdate_SwarmModeThreadsTagThroughDiscovery(t *testing.T) {
	finder := &fakeFinder{swarmShaped: true}
	h := api.NewHandlers(finder, &fakeSubmitter{}, &fakePinger{}, "v0.0.0", "abc", "now", nil)
	body, _ := json.Marshal(api.UpdateRequest{Image: "registry.example.com/myapp", Tag: "v2"})
	req := httptest.NewRequest(http.MethodPost, "/update", bytes.NewReader(body))
	w := httptest.NewRecorder()
	h.Update(w, req)
	require.Equal(t, http.StatusOK, w.Code)
	// The fake Finder's returned Job.Image (as SwarmDiscovery would build
	// it) reflects the image argument it received from the handler.
	// Asserting on the captured argument proves the full request ->
	// discovery flow carries the tag through to what would reach the
	// SwarmExecutor.
	require.Equal(t, "registry.example.com/myapp:v2", finder.gotImage)
}

func TestVersion(t *testing.T) {
	h := api.NewHandlers(&fakeFinder{}, &fakeSubmitter{}, &fakePinger{}, "v1.2.3", "abcdef", "2026-05-22T00:00:00Z", nil)
	req := httptest.NewRequest(http.MethodGet, "/version", nil)
	w := httptest.NewRecorder()
	h.Version(w, req)
	require.Equal(t, http.StatusOK, w.Code)
	resp := decode[api.VersionResponse](t, w.Body)
	require.Equal(t, "v1.2.3", resp.Version)
}