package main

import (
	"encoding/json"
	"fmt"
	"math/rand/v2"
	"net/http"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"testing"

	"github.com/stretchr/testify/require"
)

// probeMessages is the length of the generated log for the live probe.
const probeMessages = 1000

// TestProbeLogHasTheSyntheticMix checks that the generated log has readable
// ASCII text with the mix of kinds and sizes of the synthetic log. When
// ONECHAT_PROBE_LOG names a file, the test also writes the log there, one
// message {kind, text} per line, for "onechat probe".
func TestProbeLogHasTheSyntheticMix(t *testing.T) {
	messages := probeLog(probeMessages)
	require.Len(t, messages, probeMessages)

	counts := make(map[string]int)
	long := 0
	for _, message := range messages {
		counts[message.Kind]++
		require.True(t, kinds[message.Kind], message.Kind)
		require.NotEmpty(t, message.Text)
		for _, char := range message.Text {
			require.True(t, char == '\n' || (char >= ' ' && char <= '~'), "character %q", char)
		}

		if len(message.Text) >= 30000 {
			long++
		}

		if message.Kind == "work" {
			require.True(t, strings.HasPrefix(message.Text, "["), message.Text)
		}
	}

	require.Greater(t, counts["user"], 20)
	require.Greater(t, counts["tool"], 300)
	require.Greater(t, counts["echo"], 300)
	require.Greater(t, long, 2)
	require.Equal(t, messages, probeLog(probeMessages))

	path := os.Getenv("ONECHAT_PROBE_LOG")
	if path == "" {
		return
	}

	var data strings.Builder
	for _, message := range messages {
		line, err := json.Marshal(message)
		require.NoError(t, err)

		data.Write(line)
		data.WriteByte('\n')
	}

	require.NoError(t, os.WriteFile(path, []byte(data.String()), 0o600))
}

func TestProbeStopRules(t *testing.T) {
	quota := func(primary, secondary string) usageRecord {
		return usageRecord{
			Quota: map[string]string{
				"x-codex-primary-used-percent":   primary,
				"x-codex-secondary-used-percent": secondary,
				"x-codex-plan-type":              "plus",
			},
		}
	}

	testCases := []struct {
		name    string
		records []usageRecord
		want    string
	}{
		{
			name:    "no calls",
			records: nil,
			want:    "",
		},
		{
			name:    "growth within the limit",
			records: []usageRecord{quota("10", "40"), quota("25", "41")},
			want:    "",
		},
		{
			name:    "growth over the limit",
			records: []usageRecord{quota("10", "40"), quota("12", "55.5")},
			want:    "x-codex-secondary-used-percent grew from 40 to 55.5",
		},
		{
			name: "failed call",
			records: []usageRecord{quota("10", "40"), {
				Status: 400,
				Error:  "model call: HTTP 400",
			}},
			want: "call failed: model call: HTTP 400",
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			require.Equal(t, tc.want, probeStop(tc.records))
		})
	}
}

func TestProbeRunStopsWhenTheQuotaGrows(t *testing.T) {
	server := newFakeResponses(t)
	server.reply = func(w http.ResponseWriter, call fakeCall) {
		w.Header().Set("X-Codex-Primary-Used-Percent", strconv.Itoa(10+call.number))
		writeEvents(w, completedEvent([]any{messageItem(strings.Repeat("s", 400))}, 1000, 800, 50))
	}

	root := t.TempDir()
	usagePath := filepath.Join(root, "usage.jsonl")
	client := newClient(server.URL, apiKey(testKey), "onechat-"+probeName, usagePath)
	memory, err := openMemory(t.Context(), root, newTestClock().Now, newCompactor(client, probeName, defaultConfig().Compactor))
	require.NoError(t, err)

	appended, stop := runProbe(t.Context(), memory, probeLog(probeMessages), usagePath)
	sizes, err := modelLines(memory)
	require.NoError(t, err)
	require.NoError(t, memory.Close())

	require.Contains(t, stop, "x-codex-primary-used-percent grew from 10 to")
	require.Less(t, appended, probeMessages)
	require.NotEmpty(t, sizes)

	records, err := readUsageFile(usagePath)
	require.NoError(t, err)
	require.Greater(t, len(records), int(probeQuotaLimit))

	var report strings.Builder
	require.NoError(t, writeProbeReport(&report, appended, stop, records, sizes))
	require.Contains(t, report.String(), "stopped early: ")
	require.Contains(t, report.String(), "cached (80.0%)")
	require.Contains(t, report.String(), "line bytes: min 400, median 400, mean 400, max 400, 0 over 512")
	require.Contains(t, report.String(), "quota at the first call: primary-used-percent=10")
}

// probeLog returns count messages of made-up work on a small bakery order
// system, with the mix of kinds and sizes of syntheticMessage. The same count
// always gives the same log.
func probeLog(count int) []probeEntry {
	g := probeWriter{
		random: rand.New(rand.NewPCG(7, 11)),
	}

	messages := make([]probeEntry, count)
	for id := range messages {
		kind, text := g.message()
		messages[id] = probeEntry{
			Kind: kind,
			Text: text,
		}
	}

	return messages
}

// probeWriter writes readable made-up messages.
type probeWriter struct {
	random *rand.Rand
}

func (g *probeWriter) message() (string, string) {
	roll := g.random.IntN(100)
	switch {
	case roll < 5:
		return "user", g.fill(g.userLine, 10+g.random.IntN(200))
	case roll < 10:
		return "reply", g.fill(g.replyLine, 100+g.random.IntN(1500))
	case roll < 12:
		return "note", g.fill(g.noteLine, 50+g.random.IntN(600))
	case roll < 13:
		return "work", "[" + g.pick(people) + "] report: " + g.fill(g.replyLine, 300+g.random.IntN(3000))
	case roll < 56:
		return "tool", g.toolCall(60 + g.random.IntN(400))
	case roll < 57:
		return "echo", g.fill(g.outputLine, 30000+g.random.IntN(30000))
	default:
		return "echo", g.fill(g.outputLine, 20+g.random.IntN(4000))
	}
}

// fill joins lines of write until the text has about size bytes.
func (g *probeWriter) fill(write func() string, size int) string {
	var text strings.Builder
	for text.Len() < size {
		if text.Len() > 0 {
			text.WriteByte(' ')
		}

		text.WriteString(write())
	}

	return text.String()
}

func (g *probeWriter) userLine() string {
	return g.pick([]string{
		fmt.Sprintf("Please check why the %s %s.", g.pick(things), g.pick(problems)),
		fmt.Sprintf("Move the %s to %s before %s.", g.pick(things), g.pick(places), g.pick(days)),
		fmt.Sprintf("Thanks, that works. Next, %s.", g.pick(tasks)),
		fmt.Sprintf("No, keep the old %s. %s asked for it.", g.pick(things), g.pick(people)),
		fmt.Sprintf("How many %s orders came in on %s?", g.pick(breads), g.pick(days)),
	})
}

func (g *probeWriter) replyLine() string {
	return g.pick([]string{
		fmt.Sprintf("I looked at %s. The %s %s because %s.", g.pick(files), g.pick(things), g.pick(problems), g.pick(causes)),
		fmt.Sprintf("I changed %s, and the tests pass now.", g.pick(changes)),
		fmt.Sprintf("There were %d %s orders on %s, %d of them late.", 10+g.random.IntN(90), g.pick(breads), g.pick(days), g.random.IntN(10)),
		fmt.Sprintf("Open question: should %s get %s?", g.pick(people), g.pick(tasks)),
	})
}

func (g *probeWriter) noteLine() string {
	return g.pick([]string{
		fmt.Sprintf("%s prefers %s.", g.pick(people), g.pick(preferences)),
		fmt.Sprintf("The bakery opens at %d and closes at %d on %s.", 5+g.random.IntN(3), 17+g.random.IntN(4), g.pick(days)),
	})
}

func (g *probeWriter) outputLine() string {
	return g.pick([]string{
		fmt.Sprintf("%02d:%02d order %d for %d %s, packed by %s.", 6+g.random.IntN(12), g.random.IntN(60), 1000+g.random.IntN(9000), 1+g.random.IntN(24), g.pick(breads), g.pick(people)),
		fmt.Sprintf("%s:%d: %s %s.", g.pick(files), 1+g.random.IntN(400), g.pick(things), g.pick(problems)),
		fmt.Sprintf("ok   bakery/%s %d.%03ds", g.pick(modules), g.random.IntN(3), g.random.IntN(1000)),
	})
}

// toolCall returns a tool name and its JSON input of about size bytes.
func (g *probeWriter) toolCall(size int) string {
	name := g.pick([]string{"shell", "read", "write", "edit"})
	var input map[string]string
	switch name {
	case "shell":
		input = map[string]string{"command": "grep -n '" + g.pick(things) + "' " + g.pick(files)}
	case "read":
		input = map[string]string{"path": g.pick(files)}
	default:
		input = map[string]string{
			"path": g.pick(files),
			"text": g.fill(g.replyLine, max(0, size-80)),
		}
	}

	data, err := json.Marshal(input)
	if err != nil {
		panic(err)
	}

	return name + " " + string(data)
}

func (g *probeWriter) pick(words []string) string {
	return words[g.random.IntN(len(words))]
}

var (
	people      = []string{"Mara", "Joel", "Ines", "Tomas", "Priya", "Lena"}
	breads      = []string{"rye", "sourdough", "baguette", "brioche", "spelt", "seed loaf"}
	days        = []string{"Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"}
	things      = []string{"order form", "price list", "delivery route", "stock count", "invoice export", "oven schedule"}
	problems    = []string{"shows the wrong total", "skips the last row", "is slow at noon", "loses the customer note", "rounds the tax down"}
	places      = []string{"the front page", "the weekly report", "the shared folder", "the admin menu"}
	tasks       = []string{"add a field for allergies", "send the invoices on Friday", "split the route in two", "print labels for the shelf"}
	causes      = []string{"the date has no time zone", "the cache keeps old prices", "the loop stops one row early", "the form trims the note"}
	changes     = []string{"the total to use cents", "the route to sort by street", "the export to add the tax line", "the form to keep the note"}
	preferences = []string{"short answers", "a call before a change to prices", "invoices as PDF", "reports in the morning"}
	files       = []string{"orders/form.go", "prices/list.go", "routes/plan.go", "stock/count.go", "export/invoice.go", "ovens/schedule.go"}
	modules     = []string{"orders", "prices", "routes", "stock", "export", "ovens"}
)