package recipe

import (
	"fmt"
	"io"
	"strings"
	"time"

	"gitea.lab.audasmedia.com.au/sam/artemis_control/internal/adb"
	"gitea.lab.audasmedia.com.au/sam/artemis_control/internal/ui"
)

// StepResult is the record of one executed step (FR-10).
type StepResult struct {
	Index      int           `json:"step"`
	Verb       string        `json:"verb"`
	Args       []string      `json:"args,omitempty"`
	Detail     string        `json:"detail,omitempty"`
	OK         bool          `json:"ok"`
	Error      string        `json:"error,omitempty"`
	DurationMS int64         `json:"duration_ms"`
	Duration   time.Duration `json:"-"`
}

// RunResult is the record of one whole recipe run (FR-10).
type RunResult struct {
	Task       string            `json:"task"`
	Params     map[string]string `json:"params,omitempty"`
	OK         bool              `json:"ok"`
	Error      string            `json:"error,omitempty"`
	Steps      []StepResult      `json:"steps"`
	DurationMS int64             `json:"duration_ms"`
	Duration   time.Duration     `json:"-"`
}

// Options carry the caller's parameters and where to write the step log.
type Options struct {
	Params map[string]string
	Log    io.Writer
}

// Run executes a recipe against the phone.
//
// It refuses to start on a locked phone or a missing app, bounds every step
// (FR-11), and reports the reason for the first failing step. A run never
// returns an error silently: the returned RunResult always says what happened.
func Run(r *adb.Runner, rec *Recipe, opts Options) *RunResult {
	started := time.Now()
	params := opts.Params
	if params == nil {
		params = map[string]string{}
	}
	res := &RunResult{Task: rec.Task, Params: params}
	defer func() {
		res.Duration = time.Since(started)
		res.DurationMS = res.Duration.Milliseconds()
	}()

	logf := func(format string, args ...any) {
		if opts.Log != nil {
			fmt.Fprintf(opts.Log, format+"\n", args...)
		}
	}

	fail := func(err error) *RunResult {
		res.OK = false
		res.Error = err.Error()
		logf("FAILED %s after %s: %s", rec.Task, time.Since(started).Round(time.Millisecond), res.Error)
		return res
	}

	logf("task %s (%s)", rec.Task, rec.Description)

	if missing := rec.MissingParams(params); len(missing) > 0 {
		return fail(fmt.Errorf("missing required parameter(s): %s", strings.Join(missing, ", ")))
	}
	if rec.App != "" {
		installed, err := ui.AppInstalled(r, rec.App)
		if err != nil {
			return fail(fmt.Errorf("could not check whether %s is installed: %w", rec.App, err))
		}
		if !installed {
			return fail(fmt.Errorf("app is not installed: %s", rec.App))
		}
	}

	if err := ui.Wake(r); err != nil {
		return fail(err)
	}
	// A secure keyguard is a hard stop: Artemis has no credential and must
	// never type one (AGENTS.md section 13 Q2).
	if err := ui.RequireUnlocked(r); err != nil {
		return fail(err)
	}

	w, h, _ := ui.ScreenSize(r) // best effort: bounds checking degrades gracefully

	deadline := started.Add(rec.TotalTimeout)
	for i := 0; i < len(rec.Steps); i++ {
		step := rec.Steps[i]
		var sr StepResult
		for attempt := 0; ; attempt++ {
			if remaining := time.Until(deadline); remaining <= 0 {
				return fail(fmt.Errorf("recipe timed out after %s at step %d (%s)", rec.TotalTimeout, i+1, step.Verb))
			}
			sr = executeStep(r, rec, step, i, params, w, h, deadline, logf)
			res.Steps = append(res.Steps, sr)
			if sr.OK {
				break
			}
			// A wait step with "retry N" presses the step above again: on a
			// busy phone a tap can be delivered but never acted on, or dropped.
			if attempt >= step.Retry {
				return fail(fmt.Errorf("step %d (%s %s) failed: %s", i+1, step.Verb, strings.Join(step.Args, " "), sr.Error))
			}
			if i == 0 {
				return fail(fmt.Errorf("step %d: retry needs a step above it to repeat", i+1))
			}
			logf("  step %d %s: retrying, pressing %s again", i+1, step.Verb, rec.Steps[i-1].Verb)
			again := executeStep(r, rec, rec.Steps[i-1], i-1, params, w, h, deadline, logf)
			res.Steps = append(res.Steps, again)
			if !again.OK {
				// The wait is the real failure; the repeat just could not run.
				return fail(fmt.Errorf("step %d (%s %s) failed: %s; repeating %s failed too: %s",
					i+1, step.Verb, strings.Join(step.Args, " "), sr.Error, rec.Steps[i-1].Verb, again.Error))
			}
		}
	}

	res.OK = true
	logf("OK %s in %s", rec.Task, time.Since(started).Round(time.Millisecond))
	return res
}

func executeStep(r *adb.Runner, rec *Recipe, step Step, index int, params map[string]string,
	w, h int, deadline time.Time, logf func(string, ...any)) (sr StepResult) {

	started := time.Now()
	sr = StepResult{Index: index + 1, Verb: step.Verb, Args: step.Args}
	defer func() {
		sr.Duration = time.Since(started)
		sr.DurationMS = sr.Duration.Milliseconds()
	}()

	timeout := step.Timeout
	if timeout <= 0 {
		timeout = rec.StepTimeout
	}
	if remaining := time.Until(deadline); timeout > remaining {
		timeout = remaining
	}
	if timeout <= 0 {
		sr.Error = "no time left in the recipe budget"
		return sr
	}

	args := make([]string, len(step.Args))
	for i, a := range step.Args {
		v, err := Substitute(a, params)
		if err != nil {
			sr.Error = err.Error()
			return sr
		}
		args[i] = v
	}

	stepErr := func() error {
		switch step.Verb {
		case "launch":
			pkg := rec.App
			if len(args) == 1 {
				pkg = args[0]
			}
			if pkg == "" {
				return fmt.Errorf("no app named: add an \"app:\" setting or pass a package")
			}
			if err := ui.Launch(r, pkg); err != nil {
				return err
			}
			sr.Detail = "launched " + pkg
			return nil

		case "foreground":
			// Confirm the recipe's app is really in front. Without this, a text
			// like "Search" can match whatever app happened to be open.
			pkg := rec.App
			if len(args) == 1 {
				pkg = args[0]
			}
			if pkg == "" {
				return fmt.Errorf("foreground needs an app: add an \"app:\" setting or pass a package")
			}
			fgDeadline := time.Now().Add(timeout)
			for {
				fg, ferr := ui.ForegroundPackage(r)
				if ferr == nil && fg == pkg {
					sr.Detail = "foreground is " + pkg
					return nil
				}
				if time.Now().After(fgDeadline) {
					got := "unknown"
					if ferr == nil {
						got = fg
					}
					return fmt.Errorf("%s never came to the foreground within %s (foreground=%s)", pkg, timeout, got)
				}
				time.Sleep(ui.PollInterval)
			}

		case "wait":
			node, err := ui.WaitForText(r, args[0], step.Exact, timeout)
			if err != nil {
				return describeFailure(r, rec, err)
			}
			sr.Detail = "found " + node.Label()
			return nil

		case "playing":
			// The screen is not a trustworthy place to read playback: Spotify's
			// transport button keeps the label "Play" while music is playing.
			// Ask the media session instead, and confirm the track title.
			pkg := rec.App
			if len(args) == 2 {
				pkg = args[1]
			}
			if pkg == "" {
				return fmt.Errorf("playing needs an app: add an \"app:\" setting")
			}
			checkDeadline := time.Now().Add(timeout)
			var last *ui.Playback
			for {
				state, err := ui.PlaybackState(r, pkg)
				if err != nil {
					return err
				}
				last = state
				if state.Playing() && state.Title != "" {
					matched, total := ui.MatchesText(state.Title, args[0])
					if total > 0 && matched*2 >= total {
						sr.Detail = fmt.Sprintf("%s is playing %q", pkg, state.Title)
						return nil
					}
				}
				if time.Now().After(checkDeadline) {
					return fmt.Errorf("%s is not playing %q within %s (%s)", pkg, args[0], timeout, last)
				}
				time.Sleep(ui.PollInterval)
			}

		case "wait_gone":
			if err := ui.WaitForNoText(r, args[0], step.Exact, timeout); err != nil {
				return describeFailure(r, rec, err)
			}
			sr.Detail = fmt.Sprintf("%q is gone", args[0])
			return nil

		case "tap":
			return tapByText(r, rec, args[0], step.Exact, timeout, &sr)

		case "tap_if":
			// Tap only if the text is already on screen. This makes a recipe
			// tolerant of a screen that remembers state, without ever tapping
			// something that was not matched by text.
			h, err := ui.Dump(r)
			if err != nil {
				return err
			}
			matches := h.FindText(args[0], step.Exact)
			if len(matches) == 0 {
				sr.Detail = fmt.Sprintf("%q not on screen, skipped", args[0])
				return nil
			}
			node, err := ui.TapNode(r, matches)
			if err != nil {
				return err
			}
			cx, cy, _ := node.Center()
			sr.Detail = fmt.Sprintf("tapped %q at (%d,%d)", args[0], cx, cy)
			return nil

		case "tap_row":
			return tapRow(r, rec, args[0], timeout, w, h, &sr)

		case "type":
			if err := ui.Type(r, args[0]); err != nil {
				return err
			}
			sr.Detail = fmt.Sprintf("typed %d characters", len(args[0]))
			return nil

		case "key":
			return sendKey(r, args[0], &sr)

		case "back":
			if err := ui.Back(r); err != nil {
				return err
			}
			sr.Detail = "pressed back"
			return nil

		case "home":
			if err := ui.Home(r); err != nil {
				return err
			}
			sr.Detail = "pressed home"
			return nil

		case "sleep":
			time.Sleep(timeout)
			sr.Detail = "slept " + timeout.String()
			return nil
		}
		return fmt.Errorf("unknown step verb %q", step.Verb)
	}()

	if stepErr != nil {
		sr.OK = false
		sr.Error = stepErr.Error()
		logf("  step %d %s %v: %s", sr.Index, step.Verb, args, sr.Error)
		return sr
	}

	sr.OK = true
	sr.Duration = time.Since(started)
	sr.DurationMS = sr.Duration.Milliseconds()
	logf("  step %d %s %v: ok (%s)", sr.Index, step.Verb, args, sr.Duration.Round(time.Millisecond))
	return sr
}

// tapByText finds an element by text and taps its centre (FR-4).
//
// The element is looked up twice: once to wait for it, and again immediately
// before the tap, so the coordinates come from the newest dump. On a busy
// phone the first dump can be seconds old by the time the tap is sent.
func tapByText(r *adb.Runner, rec *Recipe, query string, exact bool, timeout time.Duration, sr *StepResult) error {
	if _, err := ui.WaitForText(r, query, exact, timeout); err != nil {
		return describeFailure(r, rec, err)
	}
	h, err := ui.Dump(r)
	if err != nil {
		return err
	}
	matches := h.FindText(query, exact)
	if len(matches) == 0 {
		return describeFailure(r, rec, fmt.Errorf("element with text %q disappeared before the tap", query))
	}
	node, err := ui.TapNode(r, matches)
	if err != nil {
		return err
	}
	cx, cy, _ := node.Center()
	sr.Detail = fmt.Sprintf("tapped %q at (%d,%d) %s", query, cx, cy, node.Label())
	return nil
}

// tapRow taps the list row that best matches the query. It retries the dump
// until a matching row is on screen, then taps a point derived from that row's
// own bounds.
func tapRow(r *adb.Runner, rec *Recipe, query string, timeout time.Duration, w, h int, sr *StepResult) error {
	deadline := time.Now().Add(timeout)
	var lastErr error
	for time.Now().Before(deadline) {
		hier, err := ui.Dump(r)
		if err == nil {
			row, rerr := hier.BestRow(query, rec.RowID, w, h)
			if rerr == nil {
				if err := ui.Tap(r, row.Centre.X, row.Centre.Y); err != nil {
					return err
				}
				sr.Detail = fmt.Sprintf("tapped row %q at (%d,%d) from %s", row.Title, row.Centre.X, row.Centre.Y,
					strings.Join(row.Texts, " / "))
				return nil
			}
			lastErr = rerr
		} else {
			lastErr = err
		}
		time.Sleep(ui.PollInterval)
	}
	if lastErr == nil {
		lastErr = fmt.Errorf("no result row matches %q", query)
	}
	return describeFailure(r, rec, lastErr)
}

func sendKey(r *adb.Runner, name string, sr *StepResult) error {
	codes := map[string]int{
		"enter":  ui.KeyEnter,
		"back":   ui.KeyBack,
		"home":   ui.KeyHome,
		"power":  26,
		"wakeup": ui.KeyWakeup,
		"escape": 111,
	}
	code, ok := codes[strings.ToLower(name)]
	if !ok {
		return fmt.Errorf("unknown key %q", name)
	}
	if err := ui.KeyEvent(r, code); err != nil {
		return err
	}
	sr.Detail = "pressed " + strings.ToLower(name)
	return nil
}

// describeFailure turns a step failure into a clean, named failure (FR-8).
//
// A guard match wins: "Spotify is signed out" is far more useful than "text
// Search did not appear". Otherwise the message names the screen that was on
// the phone when the step gave up.
func describeFailure(r *adb.Runner, rec *Recipe, err error) error {
	if err == nil {
		return nil
	}
	h, dumpErr := ui.Dump(r)
	if dumpErr == nil {
		for _, g := range rec.Guards {
			if len(h.FindText(g.Text, false)) > 0 {
				return fmt.Errorf("%s (phone is showing %q): %w", g.Reason, g.Text, err)
			}
		}
	}
	screen := describeScreen(r, h, dumpErr)
	if screen == "" {
		return err
	}
	return fmt.Errorf("%w; %s", err, screen)
}

// describeScreen names the screen Artemis gave up on: the foreground package
// plus the first visible lines of text.
func describeScreen(r *adb.Runner, h *ui.Hierarchy, dumpErr error) string {
	var parts []string
	if fg, err := ui.ForegroundPackage(r); err == nil {
		parts = append(parts, "foreground="+fg)
	}
	if dumpErr == nil && h != nil {
		var labels []string
		for _, n := range h.TextNodes() {
			label := strings.TrimSpace(n.Text)
			if label == "" {
				label = strings.TrimSpace(n.ContentDesc)
			}
			if label == "" || len(label) > 60 {
				continue
			}
			labels = append(labels, fmt.Sprintf("%q", label))
			if len(labels) == 6 {
				break
			}
		}
		if len(labels) > 0 {
			parts = append(parts, "screen shows: "+strings.Join(labels, ", "))
		}
	}
	return strings.Join(parts, "; ")
}