package environment

import (
	"context"
	"os"
	"path/filepath"
	"runtime"
	"testing"
	"time"
)

func TestProbeSnapshotServesAcrossRestartsWithoutReprobing(t *testing.T) {
	resetProbeCacheForTest(t, time.Unix(1000, 0))
	dir := t.TempDir()
	snapDir := t.TempDir()
	toolPath := writeProbeTool(t, filepath.Join(dir, "snaptool"), "snaptool 1.0")
	opts := ProbeOptions{Overrides: map[string]string{"snaptool": toolPath}, SnapshotDir: snapDir}
	commands := []string{"snaptool --version"}

	first := RunProbesWithOptions(context.Background(), commands, opts)
	if len(first) != 1 || !first[0].Found || first[0].Output != "snaptool 1.0" {
		t.Fatalf("first run = %+v, want found snaptool 1.0", first)
	}
	sectionBefore := FormatSection(first, "test/os", "/bin/sh", nil)

	// Simulate a process restart: in-memory cache gone, and the tool binary
	// gone too — a live probe would now say "not found". The persisted
	// snapshot must answer instead, byte-identically.
	resetProbeCacheForTest(t, time.Unix(2000, 0))
	if err := os.Remove(toolPath); err != nil {
		t.Fatalf("remove tool: %v", err)
	}
	second := RunProbesWithOptions(context.Background(), commands, opts)
	if len(second) != 1 || !second[0].Found || second[0].Output != "snaptool 1.0" {
		t.Fatalf("post-restart run = %+v, want snapshot-served snaptool 1.0", second)
	}
	if sectionAfter := FormatSection(second, "test/os", "/bin/sh", nil); sectionAfter != sectionBefore {
		t.Fatalf("environment section changed across restart:\nbefore: %s\nafter:  %s", sectionBefore, sectionAfter)
	}
}

func TestProbeSnapshotExpiresAndAdoptsDefinitiveChanges(t *testing.T) {
	resetProbeCacheForTest(t, time.Unix(1000, 0))
	dir := t.TempDir()
	snapDir := t.TempDir()
	toolPath := writeProbeTool(t, filepath.Join(dir, "exptool"), "exptool 1.0")
	opts := ProbeOptions{Overrides: map[string]string{"exptool": toolPath}, SnapshotDir: snapDir}
	commands := []string{"exptool --version"}

	if first := RunProbesWithOptions(context.Background(), commands, opts); !first[0].Found {
		t.Fatalf("first run = %+v, want found", first)
	}

	// Past the snapshot TTL a live probe runs again; a definitive change (the
	// tool now reports a new version) is adopted and re-persisted.
	resetProbeCacheForTest(t, time.Unix(1000, 0).Add(probeSnapshotTTL+time.Hour))
	writeProbeTool(t, filepath.Join(dir, "exptool"), "exptool 2.0")
	second := RunProbesWithOptions(context.Background(), commands, opts)
	if !second[0].Found || second[0].Output != "exptool 2.0" {
		t.Fatalf("post-TTL run = %+v, want refreshed exptool 2.0", second)
	}

	// The refreshed snapshot serves the new bytes across the next restart.
	resetProbeCacheForTest(t, time.Unix(1000, 0).Add(probeSnapshotTTL+2*time.Hour))
	if err := os.Remove(toolPath); err != nil {
		t.Fatalf("remove tool: %v", err)
	}
	third := RunProbesWithOptions(context.Background(), commands, opts)
	if !third[0].Found || third[0].Output != "exptool 2.0" {
		t.Fatalf("post-refresh restart = %+v, want snapshot-served exptool 2.0", third)
	}
}

func TestProbeSnapshotKeepsFoundOverTransientFailure(t *testing.T) {
	resetProbeCacheForTest(t, time.Unix(1000, 0))
	dir := t.TempDir()
	snapDir := t.TempDir()
	toolPath := writeProbeTool(t, filepath.Join(dir, "flaptool"), "flaptool 1.0")
	opts := ProbeOptions{Overrides: map[string]string{"flaptool": toolPath}, SnapshotDir: snapDir}
	commands := []string{"flaptool --version"}

	if first := RunProbesWithOptions(context.Background(), commands, opts); !first[0].Found {
		t.Fatalf("first run = %+v, want found", first)
	}

	// Past the TTL the live probe fails transiently (nonzero exit): the merge
	// keeps the previous successful observation so the rendered section — and
	// with it the cached prompt prefix — does not flap. Overwrite the tool in
	// place so the fingerprint (command + override path) stays identical to
	// the snapshot's.
	resetProbeCacheForTest(t, time.Unix(1000, 0).Add(probeSnapshotTTL+time.Hour))
	if err := os.Remove(toolPath); err != nil {
		t.Fatalf("remove tool: %v", err)
	}
	body := "#!/bin/sh\nexit 1\n"
	if runtime.GOOS == "windows" {
		body = "@exit /b 1\r\n"
	}
	if err := os.WriteFile(toolPath, []byte(body), 0o755); err != nil {
		t.Fatalf("write failing tool: %v", err)
	}
	second := RunProbesWithOptions(context.Background(), commands, opts)
	if !second[0].Found || second[0].Output != "flaptool 1.0" {
		t.Fatalf("transient failure run = %+v, want previous found result kept", second)
	}

	// A definitive "not found" (override pointing at a missing binary) is
	// adopted — genuinely uninstalled tools must not be resurrected forever.
	resetProbeCacheForTest(t, time.Unix(1000, 0).Add(2*probeSnapshotTTL+2*time.Hour))
	if err := os.Remove(toolPath); err != nil {
		t.Fatalf("remove tool: %v", err)
	}
	third := RunProbesWithOptions(context.Background(), commands, opts)
	if third[0].Found || third[0].Error != "not found" {
		t.Fatalf("definitive removal run = %+v, want not found adopted", third)
	}
}

func TestMergeProbeSnapshotOnlyOverlaysTransientFailures(t *testing.T) {
	previous := []ProbeResult{
		{Command: "go version", Binary: "go", Found: true, Output: "go1.24"},
		{Command: "docker --version", Binary: "docker", Found: true, Output: "Docker 27"},
		{Command: "node --version", Binary: "node", Found: true, Output: "v22"},
	}
	fresh := []ProbeResult{
		{Command: "go version", Binary: "go", Error: "timeout"},
		{Command: "docker --version", Binary: "docker", Error: "exit exit status 1"},
		{Command: "node --version", Binary: "node", Error: "not found"},
	}
	merged := mergeProbeSnapshot(previous, fresh)
	byCommand := map[string]ProbeResult{}
	for _, r := range merged {
		byCommand[r.Command] = r
	}
	if r := byCommand["go version"]; !r.Found || r.Output != "go1.24" {
		t.Fatalf("timeout overlay = %+v, want previous found kept", r)
	}
	if r := byCommand["docker --version"]; !r.Found || r.Output != "Docker 27" {
		t.Fatalf("exit overlay = %+v, want previous found kept", r)
	}
	if r := byCommand["node --version"]; r.Found || r.Error != "not found" {
		t.Fatalf("not-found overlay = %+v, want definitive result adopted", r)
	}
}