package main

import (
	"bytes"
	"errors"
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"io"
	"strconv"
	"strings"
	"testing"

	"textmachine/backend/internal/pipeline"
)

// invocation_test.go pins the frozen CLI parsing contract (package №4): exit code 2
// is exclusive to completed-with-flags (a bad flag → 1), validation order,
// the redrive selector, the stdlib flag's diagnostics sink.

func TestParseNoArgsUsage(t *testing.T) {
	_, err := parseInvocation(nil, &bytes.Buffer{})
	// The command list gained `export` (D39 слой 6 read-only surface), then `manifest` (backlog row 100
	// — the $0 producer of the chapter/chunk manifest), and then the three the line had silently never
	// learned: `backup`/`migrate` (the deploy step, row 174) and `seed-lint`, which gets its own clause
	// because it takes --seed rather than --config (row 176, sanctioned by D39.134 п.3). `bank-apply` is
	// the sixth (D39.156 — the inbound door for the owner's bank decisions) and gets its own clause for
	// the same reason seed-lint does: it needs --decisions on top of --config. Every one is a deliberate
	// contract extension and the rest of the usage text stays frozen.
	if err == nil || err.Error() != "usage: tmctl <translate|report|status|export|redrive|manifest|backup|migrate> --config book.yaml | tmctl bank-apply --config book.yaml --decisions decisions.json | tmctl seed-lint --seed glossary.yaml" {
		t.Fatalf("usage error text is frozen, got: %v", err)
	}
	// The line and the dispatch switch are the same list: a command reachable in run() and missing here
	// is exactly the defect row 176 recorded, and it grew back three times.
	for _, cmd := range dispatchCommands {
		if !strings.Contains(err.Error(), cmd) {
			t.Errorf("the usage line must name every dispatchable command; %q is missing from: %s", cmd, err.Error())
		}
	}
}

func TestParseMissingConfig(t *testing.T) {
	// Validation order is frozen: `tmctl bogus` without --config complains about config,
	// NOT about the unknown command (that's caught later, in run()'s dispatch switch).
	for _, args := range [][]string{{"translate"}, {"bogus"}} {
		_, err := parseInvocation(args, &bytes.Buffer{})
		if err == nil || err.Error() != "--config book.yaml is required" {
			t.Fatalf("args %v: missing-config error text is frozen, got: %v", args, err)
		}
	}
}

func TestParseBadFlagIsExit1NotExit2(t *testing.T) {
	var diag bytes.Buffer
	_, err := parseInvocation([]string{"status", "--no-such-flag"}, &diag)
	if err == nil {
		t.Fatal("a bad flag must be an error")
	}
	// The collision guard: a parse failure maps to exit 1 — NEVER to 2, which is
	// exclusive to completed-with-flags (the reason for ContinueOnError).
	if code := exitCode(err); code != 1 {
		t.Fatalf("bad flag must exit 1, got %d", code)
	}
	// The stdlib's diagnostics ("flag provided but not defined" + usage) must land
	// in the provided writer (main passes os.Stderr).
	if !strings.Contains(diag.String(), "flag provided but not defined") {
		t.Fatalf("flag diagnostics must go to the provided writer, got: %q", diag.String())
	}
}

func TestParseUnknownCommandPassesThrough(t *testing.T) {
	inv, err := parseInvocation([]string{"bogus", "--config", "b.yaml"}, &bytes.Buffer{})
	if err != nil {
		t.Fatalf("command name is validated in the dispatch switch, not the parser: %v", err)
	}
	if inv.cmd != "bogus" || inv.cfgPath != "b.yaml" {
		t.Fatalf("inv = %+v", inv)
	}
}

func TestParseRedriveSelectorDefaults(t *testing.T) {
	inv, err := parseInvocation([]string{"redrive", "--config", "b.yaml"}, &bytes.Buffer{})
	if err != nil {
		t.Fatal(err)
	}
	want := pipeline.RedriveSelector{Chapter: -1, ChunkIdx: -1, Reason: "", DryRun: false}
	if inv.sel != want {
		t.Fatalf("default selector must be «any» (-1/-1/\"\"/false), got %+v", inv.sel)
	}
	if inv.resnapshot {
		t.Fatal("resnapshot must default to false")
	}
}

func TestParseRedriveSelectorExplicit(t *testing.T) {
	inv, err := parseInvocation([]string{"redrive", "--config", "b.yaml",
		"--chapter", "3", "--chunk", "7", "--reason", "soft_refusal", "--dry-run", "--resnapshot"}, &bytes.Buffer{})
	if err != nil {
		t.Fatal(err)
	}
	want := pipeline.RedriveSelector{Chapter: 3, ChunkIdx: 7, Reason: "soft_refusal", DryRun: true}
	if inv.sel != want {
		t.Fatalf("selector wiring lost a flag (regression class D20.4 «parsed but ignored»): %+v", inv.sel)
	}
	// D20.4 regression class: --resnapshot was once parsed but never wired.
	if !inv.resnapshot {
		t.Fatal("--resnapshot must reach the invocation")
	}
}

// TestParseAcceptRebillForms pins the OPTIONAL-VALUE contract of --accept-rebill[=usd] (D20.2-Q2):
// bare = consent to the whole projected amount, `=usd` = consent only up to that ceiling, absent =
// no consent. The three states are distinct because the gate treats them differently.
func TestParseAcceptRebillForms(t *testing.T) {
	for _, tc := range []struct {
		args []string
		want pipeline.RebillConsent
	}{
		{[]string{"translate", "--config", "b.yaml"}, pipeline.RebillConsent{}},
		{[]string{"translate", "--config", "b.yaml", "--accept-rebill"}, pipeline.RebillConsent{Given: true}},
		{[]string{"translate", "--config", "b.yaml", "--accept-rebill=1.50"}, pipeline.RebillConsent{Given: true, Capped: true, CapUSD: 1.50}},
		// An explicit ZERO ceiling is a real answer ("only if it costs nothing"), not "no flag".
		{[]string{"translate", "--config", "b.yaml", "--accept-rebill=0"}, pipeline.RebillConsent{Given: true, Capped: true, CapUSD: 0}},
		{[]string{"redrive", "--config", "b.yaml", "--accept-rebill=0.25", "--resnapshot"}, pipeline.RebillConsent{Given: true, Capped: true, CapUSD: 0.25}},
	} {
		inv, err := parseInvocation(tc.args, &bytes.Buffer{})
		if err != nil {
			t.Fatalf("%v: %v", tc.args, err)
		}
		if inv.acceptRebill != tc.want {
			t.Errorf("%v → %+v, want %+v", tc.args, inv.acceptRebill, tc.want)
		}
	}
}

// TestParseAcceptRebillSpaceFormRefused is the money trap of an IsBoolFlag optional value: written with
// a SPACE the amount does not bind, the flag reads as bare, and a capped consent silently becomes an
// unlimited one. It must be an error, not a $-sized surprise.
func TestParseAcceptRebillSpaceFormRefused(t *testing.T) {
	_, err := parseInvocation([]string{"translate", "--config", "b.yaml", "--accept-rebill", "1.50"}, &bytes.Buffer{})
	if err == nil {
		t.Fatal("`--accept-rebill 1.50` must not silently read as an UNLIMITED consent")
	}
	if !strings.Contains(err.Error(), "--accept-rebill=1.50") {
		t.Errorf("the error must show the correct spelling; got: %v", err)
	}
	if code := exitCode(err); code != 1 {
		t.Errorf("a parse error is exit 1, got %d", code)
	}
	// The same stray argument WITHOUT the bare flag stays tolerated (the frozen contract is untouched).
	if _, err := parseInvocation([]string{"translate", "--config", "b.yaml", "stray"}, &bytes.Buffer{}); err != nil {
		t.Errorf("a stray argument outside the --accept-rebill spelling must stay tolerated: %v", err)
	}
}

// TestParseAcceptRebillRejectsBadCeiling: a ceiling that is not a non-negative number is a typo about
// MONEY — refuse rather than fall back to some default consent.
func TestParseAcceptRebillRejectsBadCeiling(t *testing.T) {
	for _, bad := range []string{"abc", "-1", "1,50", "NaN", "Inf"} {
		var diag bytes.Buffer
		_, err := parseInvocation([]string{"translate", "--config", "b.yaml", "--accept-rebill=" + bad}, &diag)
		if err == nil {
			t.Errorf("--accept-rebill=%s must be refused", bad)
		}
	}
}

func TestExitCodeContract(t *testing.T) {
	if exitCode(nil) != 0 {
		t.Fatal("nil → 0")
	}
	if exitCode(errors.New("boom")) != 1 {
		t.Fatal("generic error → 1")
	}
	sentinel := &pipeline.CompletedWithFlags{Flagged: 2, Total: 5}
	if exitCode(sentinel) != 2 {
		t.Fatal("sentinel → 2")
	}
	// The sentinel must survive %w-wrapping (errors.As, not a type switch).
	if exitCode(fmt.Errorf("outer: %w", sentinel)) != 2 {
		t.Fatal("wrapped sentinel → 2")
	}
	// R1-FL-A: a bank-mining signature stop is a DISTINCT exit code (3), not conflated with a flag (2) or a
	// crash (1), so exit-code automation can tell a sign-boundary pause from a real failure.
	sigStop := &pipeline.WaveSignatureStop{Terms: 4, SignaturePath: "/tmp/book.db.mined-signature.yaml"}
	if exitCode(sigStop) != 3 {
		t.Fatalf("signature-stop sentinel → 3, got %d", exitCode(sigStop))
	}
	if exitCode(fmt.Errorf("outer: %w", sigStop)) != 3 {
		t.Fatal("wrapped signature-stop → 3")
	}
	// The two sentinels must NOT collide: a flag stays 2 even though both are typed sentinels.
	if exitCode(sentinel) == exitCode(sigStop) {
		t.Fatal("CompletedWithFlags and WaveSignatureStop must map to different exit codes")
	}
}

// TestParseVerifyBank pins the pack-20 mode flag: CLI-only, binary, off by default, accepted on the two
// commands that run the durable loop. Off-by-default IS the contract (D39.42 п.5) — the run carries an
// unsigned bank forward unless a human asks to be stopped.
func TestParseVerifyBank(t *testing.T) {
	inv, err := parseInvocation([]string{"translate", "--config", "b.yaml"}, io.Discard)
	if err != nil {
		t.Fatal(err)
	}
	if inv.verifyBank {
		t.Fatal("the bank stop must be OFF unless asked for — a default pause is what D39.42 removed")
	}
	for _, cmd := range []string{"translate", "redrive"} {
		inv, err := parseInvocation([]string{cmd, "--config", "b.yaml", "--verify-bank"}, io.Discard)
		if err != nil {
			t.Fatalf("%s --verify-bank: %v", cmd, err)
		}
		if !inv.verifyBank {
			t.Fatalf("%s: the flag must be parsed", cmd)
		}
	}
	// It is a BOOL: it never takes a value, so the "optional value" trap that --accept-rebill needed a
	// guard for cannot exist here.
	if _, err := parseInvocation([]string{"translate", "--config", "b.yaml", "--verify-bank=1.5"}, io.Discard); err == nil {
		t.Fatal("--verify-bank must not accept a non-boolean value")
	}
}

// --- backlog row 145: the per-run ceiling flag ----------------------------------------------------

// TestParseCeilingUSD pins the flag's whole contract: absent means "the book's own ceiling stands", a
// positive amount is carried through, and every value that is not a spendable amount is REFUSED rather
// than defaulted. The refusal is the load-bearing half — Р7 forbids a ledger with no ceiling, and a
// silently-ignored `--ceiling-usd 0` would be exactly that with a flag in front of it.
func TestParseCeilingUSD(t *testing.T) {
	inv, err := parseInvocation([]string{"translate", "--config", "b.yaml"}, &bytes.Buffer{})
	if err != nil || inv.ceilingUSD != 0 {
		t.Fatalf("an absent flag must leave the ceiling unset, got %v / %v", inv.ceilingUSD, err)
	}
	inv, err = parseInvocation([]string{"translate", "--config", "b.yaml", "--ceiling-usd=1.25"}, &bytes.Buffer{})
	if err != nil || inv.ceilingUSD != 1.25 {
		t.Fatalf("--ceiling-usd=1.25 → %v / %v", inv.ceilingUSD, err)
	}
	// The space spelling binds too (unlike --accept-rebill, which is a bool-flag with an optional value).
	inv, err = parseInvocation([]string{"redrive", "--config", "b.yaml", "--ceiling-usd", "0.5"}, &bytes.Buffer{})
	if err != nil || inv.ceilingUSD != 0.5 {
		t.Fatalf("--ceiling-usd 0.5 → %v / %v", inv.ceilingUSD, err)
	}
	for _, bad := range []string{"0", "-1", "NaN", "Inf"} {
		var diag bytes.Buffer
		if _, err := parseInvocation([]string{"translate", "--config", "b.yaml", "--ceiling-usd=" + bad}, &diag); err == nil {
			t.Fatalf("--ceiling-usd=%s must be refused: a run ceiling that is not a spendable amount is not a ceiling", bad)
		} else if code := exitCode(err); code != 1 {
			t.Fatalf("--ceiling-usd=%s must exit 1, got %d", bad, code)
		}
	}
}

// TestDispatchCommandsCoversTheSwitch closes the direction the usage-line test cannot see. That test
// walks dispatchCommands and checks each name appears in the usage string, so DROPPING a command from
// the list keeps it green while the usage line silently stops mentioning a command tmctl still runs —
// exactly the defect of row 176, which grew back three times. This reads the dispatch switch itself.
func TestDispatchCommandsCoversTheSwitch(t *testing.T) {
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "main.go", nil, 0)
	if err != nil {
		t.Fatal(err)
	}
	inList := map[string]bool{}
	for _, c := range dispatchCommands {
		inList[c] = true
	}
	found := 0
	ast.Inspect(f, func(n ast.Node) bool {
		sw, ok := n.(*ast.SwitchStmt)
		if !ok {
			return true
		}
		sel, ok := sw.Tag.(*ast.SelectorExpr)
		if !ok || sel.Sel.Name != "cmd" {
			return true
		}
		for _, stmt := range sw.Body.List {
			for _, expr := range stmt.(*ast.CaseClause).List {
				lit, ok := expr.(*ast.BasicLit)
				if !ok || lit.Kind != token.STRING {
					continue
				}
				name, err := strconv.Unquote(lit.Value)
				if err != nil {
					t.Fatal(err)
				}
				found++
				if !inList[name] {
					t.Errorf("run() dispatches %q but dispatchCommands does not list it — the usage line will not name it", name)
				}
			}
		}
		return false
	})
	if found != len(dispatchCommands) {
		t.Errorf("the dispatch switch has %d commands, dispatchCommands lists %d — the two must be one list", found, len(dispatchCommands))
	}
}