// Summary: Hexai CLI runner; reads input, creates an LLM client, builds messages,
// streams or collects the model output, and prints a short summary to stderr.
package hexaicli

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"log"
	"os"
	"strings"
	"sync"
	"time"

	"codeberg.org/snonux/hexai/internal/appconfig"
	"codeberg.org/snonux/hexai/internal/editor"
	"codeberg.org/snonux/hexai/internal/llm"
	"codeberg.org/snonux/hexai/internal/llmutils"
	"codeberg.org/snonux/hexai/internal/logging"
	"codeberg.org/snonux/hexai/internal/stats"
	"codeberg.org/snonux/hexai/internal/tmux"
	"github.com/mattn/go-runewidth"
	"golang.org/x/term"
)

type requestArgs struct {
	model   string
	options []llm.RequestOption
}

type cliJob struct {
	index    int
	provider string
	entry    appconfig.SurfaceConfig
	client   llm.Client
	req      requestArgs
}

type columnPrinter struct {
	mu        sync.Mutex
	stdout    io.Writer
	columns   int
	colWidth  int
	partial   []string
	providers []string
	models    []string
}

type columnWriter struct {
	printer *columnPrinter
	index   int
}

type (
	selectionContextKey  struct{}
	configPathContextKey struct{}
)

func buildCLIJobs(cfg appconfig.App) ([]cliJob, error) {
	entries := cfg.CLIConfigs
	if len(entries) == 0 {
		entries = []appconfig.SurfaceConfig{{}}
	}
	jobs := make([]cliJob, 0, len(entries))
	for i, raw := range entries {
		entry := appconfig.SurfaceConfig{Provider: strings.TrimSpace(raw.Provider), Model: strings.TrimSpace(raw.Model), Temperature: raw.Temperature}
		provider := entry.Provider
		if provider == "" {
			provider = cfg.Provider
		}
		provider = canonicalProvider(provider)
		derived := llmutils.ConfigForProvider(cfg, provider, entry.Model)
		client, err := newClientFromApp(derived)
		if err != nil {
			return nil, err
		}
		req := buildCLIRequest(entry, provider, cfg, client)
		if strings.TrimSpace(req.model) == "" {
			req.model = strings.TrimSpace(client.DefaultModel())
		}
		jobs = append(jobs, cliJob{index: i, provider: provider, entry: entry, client: client, req: req})
	}
	return jobs, nil
}

func buildCLIRequest(entry appconfig.SurfaceConfig, provider string, cfg appconfig.App, client llm.Client) requestArgs {
	opts := make([]llm.RequestOption, 0, 2)
	if cfg.MaxTokens > 0 {
		opts = append(opts, llm.WithMaxTokens(cfg.MaxTokens))
	}
	model := strings.TrimSpace(entry.Model)
	if model == "" {
		if client != nil {
			model = strings.TrimSpace(client.DefaultModel())
		}
		if model == "" {
			model = strings.TrimSpace(llmutils.DefaultModelForProvider(cfg, provider))
		}
	}
	if entry.Model != "" {
		opts = append(opts, llm.WithModel(entry.Model))
	}
	if temp, ok := cliTemperatureFromEntry(cfg, provider, entry, model); ok {
		opts = append(opts, llm.WithTemperature(temp))
	}
	return requestArgs{model: model, options: opts}
}

func cliTemperatureFromEntry(cfg appconfig.App, provider string, entry appconfig.SurfaceConfig, model string) (float64, bool) {
	if entry.Temperature != nil {
		return *entry.Temperature, true
	}
	if cfg.CodingTemperature != nil {
		temp := *cfg.CodingTemperature
		if provider == "openai" && strings.HasPrefix(strings.ToLower(model), "gpt-5") && temp == 0.2 {
			temp = 1.0
		}
		return temp, true
	}
	if provider == "openai" && strings.HasPrefix(strings.ToLower(model), "gpt-5") {
		return 1.0, true
	}
	return 0, false
}

func canonicalProvider(name string) string {
	return llmutils.CanonicalProvider(name)
}

// Run executes the Hexai CLI behavior given arguments and I/O streams.
// It assumes flags have already been parsed by the caller.
func Run(ctx context.Context, args []string, stdin io.Reader, stdout, stderr io.Writer) error {
	// Load configuration with a logger so file-based config is respected.
	logger := log.New(stderr, "hexai ", log.LstdFlags|log.Lmsgprefix)
	configPath := configPathFromContext(ctx)
	cfg := appconfig.LoadWithOptions(logger, appconfig.LoadOptions{ConfigPath: configPath})
	if cfg.StatsWindowMinutes > 0 {
		stats.SetWindow(time.Duration(cfg.StatsWindowMinutes) * time.Minute)
	}
	jobs, err := buildCLIJobs(cfg)
	if err != nil {
		_, _ = fmt.Fprintf(stderr, logging.AnsiBase+"hexai: LLM disabled: %v"+logging.AnsiReset+"\n", err)
		return err
	}
	if selected := selectionFromContext(ctx); len(selected) > 0 {
		jobs, err = filterJobsBySelection(jobs, selected)
		if err != nil {
			_, _ = fmt.Fprintf(stderr, logging.AnsiBase+"hexai: %v"+logging.AnsiReset+"\n", err)
			return err
		}
	}
	if len(jobs) == 0 {
		return fmt.Errorf("hexai: no CLI providers configured")
	}
	// Prefer piped stdin when present; only open the editor when there are no args
	// and no stdin content available.
	input, rerr := readInput(stdin, args)
	if rerr != nil && len(args) == 0 {
		if prompt, eerr := editor.OpenTempAndEdit(nil); eerr == nil && strings.TrimSpace(prompt) != "" {
			args = []string{prompt}
			input, rerr = readInput(stdin, args)
		}
	}
	if rerr != nil {
		_, _ = fmt.Fprintln(stderr, logging.AnsiBase+rerr.Error()+logging.AnsiReset)
		return rerr
	}
	msgs := buildMessagesFromConfig(cfg, input)
	if err := runCLIJobs(ctx, jobs, msgs, input, stdout, stderr); err != nil {
		_, _ = fmt.Fprintf(stderr, logging.AnsiBase+"hexai: error: %v"+logging.AnsiReset+"\n", err)
		return err
	}
	return nil
}

// RunWithClient executes the CLI flow using an already-constructed client.
// Useful for testing and embedding.
func RunWithClient(ctx context.Context, args []string, stdin io.Reader, stdout, stderr io.Writer, client llm.Client) error {
	input, err := readInput(stdin, args)
	if err != nil {
		_, _ = fmt.Fprintln(stderr, logging.AnsiBase+err.Error()+logging.AnsiReset)
		return err
	}
	req := requestArgs{model: strings.TrimSpace(client.DefaultModel())}
	printProviderInfo(stderr, client, req.model)
	msgs := buildMessages(input)
	if err := runChat(ctx, client, req, msgs, input, stdout, stderr); err != nil {
		_, _ = fmt.Fprintf(stderr, logging.AnsiBase+"hexai: error: %v"+logging.AnsiReset+"\n", err)
		return err
	}
	return nil
}

type cliJobResult struct {
	provider string
	model    string
	output   string
	summary  string
	err      error
}

type chatRunSummary struct {
	snapshot stats.Snapshot
	sent     int
	recv     int
	scopeReq int64
	scopeRPM float64
}

func runCLIJobs(ctx context.Context, jobs []cliJob, msgs []llm.Message, input string, stdout, stderr io.Writer) error {
	results, printer := executeCLIJobs(ctx, jobs, msgs, input, stdout, stderr)
	if printer == nil {
		if err := writeCLIJobOutputs(stdout, results); err != nil {
			return err
		}
	}
	return writeCLIJobSummaries(stderr, results)
}

func executeCLIJobs(ctx context.Context, jobs []cliJob, msgs []llm.Message, input string, stdout io.Writer, stderr io.Writer) ([]*cliJobResult, *columnPrinter) {
	results := make([]*cliJobResult, len(jobs))
	printer := setupCLIPrinter(stdout, jobs)
	var wg sync.WaitGroup
	for _, job := range jobs {
		job := job
		wg.Add(1)
		printProviderInfo(stderr, job.client, job.req.model)
		go func() {
			defer wg.Done()
			results[job.index] = runSingleCLIJob(ctx, job, msgs, input, printer)
		}()
	}
	wg.Wait()
	return results, printer
}

func setupCLIPrinter(stdout io.Writer, jobs []cliJob) *columnPrinter {
	if len(jobs) == 0 {
		return nil
	}
	printer := newColumnPrinter(stdout, jobs)
	printer.PrintHeader()
	return printer
}

func runSingleCLIJob(ctx context.Context, job cliJob, msgs []llm.Message, input string, printer *columnPrinter) *cliJobResult {
	var errBuf bytes.Buffer
	var outBuf bytes.Buffer
	jobMsgs := append([]llm.Message(nil), msgs...)
	writer := io.Writer(&outBuf)
	if printer != nil {
		writer = printer.Writer(job.index)
	}
	err := runChat(ctx, job.client, job.req, jobMsgs, input, writer, &errBuf)
	if printer != nil {
		printer.Flush(job.index)
	}
	return &cliJobResult{
		provider: job.client.Name(),
		model:    job.req.model,
		output:   outBuf.String(),
		summary:  errBuf.String(),
		err:      err,
	}
}

func writeCLIJobOutputs(stdout io.Writer, results []*cliJobResult) error {
	printed := false
	for _, res := range results {
		if res == nil {
			continue
		}
		if printed {
			if _, err := io.WriteString(stdout, "\n"); err != nil {
				return err
			}
		}
		if err := writeCLIJobOutput(stdout, res); err != nil {
			return err
		}
		printed = true
	}
	return nil
}

func writeCLIJobOutput(stdout io.Writer, res *cliJobResult) error {
	heading := fmt.Sprintf("=== %s:%s ===\n", res.provider, res.model)
	if _, err := io.WriteString(stdout, heading); err != nil {
		return err
	}
	if res.output == "" {
		return nil
	}
	if _, err := io.WriteString(stdout, res.output); err != nil {
		return err
	}
	if strings.HasSuffix(res.output, "\n") {
		return nil
	}
	_, err := io.WriteString(stdout, "\n")
	return err
}

func writeCLIJobSummaries(stderr io.Writer, results []*cliJobResult) error {
	var firstErr error
	for _, res := range results {
		if res == nil {
			continue
		}
		if err := writeCLIJobSummary(stderr, res); err != nil {
			return err
		}
		if firstErr == nil && res.err != nil {
			firstErr = res.err
		}
	}
	return firstErr
}

func writeCLIJobSummary(stderr io.Writer, res *cliJobResult) error {
	summary := strings.TrimLeft(res.summary, "\n")
	if summary != "" {
		if _, err := io.WriteString(stderr, summary); err != nil {
			return err
		}
	}
	if res.err == nil {
		return nil
	}
	_, err := fmt.Fprintf(stderr, logging.AnsiBase+"hexai: provider=%s model=%s error: %v"+logging.AnsiReset+"\n", res.provider, res.model, res.err)
	return err
}

func newColumnPrinter(stdout io.Writer, jobs []cliJob) *columnPrinter {
	cols := len(jobs)
	width := detectTerminalWidth(stdout)
	if width <= 0 {
		width = 100
	}
	sepWidth := (cols - 1) * 3
	colWidth := (width - sepWidth) / cols
	if colWidth < 20 {
		colWidth = 20
	}
	providers := make([]string, cols)
	models := make([]string, cols)
	for _, job := range jobs {
		providers[job.index] = job.client.Name()
		models[job.index] = job.req.model
	}
	return &columnPrinter{
		stdout:    stdout,
		columns:   cols,
		colWidth:  colWidth,
		partial:   make([]string, cols),
		providers: providers,
		models:    models,
	}
}

func detectTerminalWidth(w io.Writer) int {
	type fder interface{ Fd() uintptr }
	if f, ok := w.(*os.File); ok {
		if width, _, err := term.GetSize(int(f.Fd())); err == nil {
			return width
		}
	}
	if f, ok := w.(fder); ok {
		if width, _, err := term.GetSize(int(f.Fd())); err == nil {
			return width
		}
	}
	return 0
}

func (cp *columnPrinter) Writer(idx int) io.Writer {
	return columnWriter{printer: cp, index: idx}
}

func (cp *columnPrinter) PrintHeader() {
	cp.mu.Lock()
	defer cp.mu.Unlock()
	combo := make([]string, cp.columns)
	for i := 0; i < cp.columns; i++ {
		provider := strings.TrimSpace(cp.providers[i])
		model := strings.TrimSpace(cp.models[i])
		switch {
		case provider != "" && model != "":
			combo[i] = provider + ":" + model
		case provider != "":
			combo[i] = provider
		case model != "":
			combo[i] = model
		default:
			combo[i] = ""
		}
	}
	cp.writeLine(combo)
	divider := make([]string, cp.columns)
	line := strings.Repeat("─", cp.colWidth)
	for i := range divider {
		divider[i] = line
	}
	cp.writeLine(divider)
}

func (cp *columnPrinter) Flush(idx int) {
	cp.mu.Lock()
	defer cp.mu.Unlock()
	if idx < 0 || idx >= len(cp.partial) {
		return
	}
	if cp.partial[idx] == "" {
		return
	}
	cp.emitJobLine(idx, cp.partial[idx])
	cp.partial[idx] = ""
}

func (w columnWriter) Write(p []byte) (int, error) {
	return w.printer.write(w.index, string(p))
}

func (cp *columnPrinter) write(idx int, data string) (int, error) {
	cp.mu.Lock()
	defer cp.mu.Unlock()
	if idx < 0 || idx >= len(cp.partial) {
		return len(data), nil
	}
	data = strings.ReplaceAll(data, "\r", "")
	cp.partial[idx] += data
	for strings.Contains(cp.partial[idx], "\n") {
		line, rest, _ := strings.Cut(cp.partial[idx], "\n")
		cp.partial[idx] = rest
		cp.emitJobLine(idx, line)
	}
	return len(data), nil
}

func (cp *columnPrinter) emitJobLine(idx int, line string) {
	segments := cp.wrap(line)
	for _, seg := range segments {
		cells := make([]string, cp.columns)
		if idx >= 0 && idx < len(cells) {
			cells[idx] = seg
		}
		cp.writeLine(cells)
	}
}

func (cp *columnPrinter) wrap(text string) []string {
	text = strings.ReplaceAll(text, "\t", "    ")
	if runewidth.StringWidth(text) <= cp.colWidth {
		return []string{text}
	}
	var lines []string
	var current strings.Builder
	width := 0
	for _, r := range text {
		rw := runewidth.RuneWidth(r)
		if width+rw > cp.colWidth && current.Len() > 0 {
			lines = append(lines, current.String())
			current.Reset()
			width = 0
		}
		current.WriteRune(r)
		width += rw
	}
	if current.Len() > 0 {
		lines = append(lines, current.String())
	}
	if len(lines) == 0 {
		lines = append(lines, "")
	}
	return lines
}

func (cp *columnPrinter) writeLine(cells []string) {
	if len(cells) < cp.columns {
		extra := make([]string, cp.columns-len(cells))
		cells = append(cells, extra...)
	}
	var builder strings.Builder
	for i := 0; i < cp.columns; i++ {
		cell := cells[i]
		width := runewidth.StringWidth(cell)
		if width > cp.colWidth {
			cell = runewidth.Truncate(cell, cp.colWidth, "…")
			width = runewidth.StringWidth(cell)
		}
		builder.WriteString(cell)
		if pad := cp.colWidth - width; pad > 0 {
			builder.WriteString(strings.Repeat(" ", pad))
		}
		if i != cp.columns-1 {
			builder.WriteString(" │ ")
		}
	}
	builder.WriteByte('\n')
	_, _ = cp.stdout.Write([]byte(builder.String()))
}

// WithCLISelection injects provider indices into the context so Run only executes those jobs.
func WithCLISelection(ctx context.Context, indices []int) context.Context {
	if ctx == nil {
		ctx = context.Background()
	}
	cpy := make([]int, len(indices))
	copy(cpy, indices)
	return context.WithValue(ctx, selectionContextKey{}, cpy)
}

// WithCLIConfigPath returns a context that carries the config file path override.
func WithCLIConfigPath(ctx context.Context, path string) context.Context {
	if ctx == nil {
		ctx = context.Background()
	}
	return context.WithValue(ctx, configPathContextKey{}, strings.TrimSpace(path))
}

func configPathFromContext(ctx context.Context) string {
	if ctx == nil {
		return ""
	}
	if v, ok := ctx.Value(configPathContextKey{}).(string); ok {
		return strings.TrimSpace(v)
	}
	return ""
}

func selectionFromContext(ctx context.Context) []int {
	if ctx == nil {
		return nil
	}
	if v, ok := ctx.Value(selectionContextKey{}).([]int); ok {
		cpy := make([]int, len(v))
		copy(cpy, v)
		return cpy
	}
	return nil
}

func filterJobsBySelection(jobs []cliJob, indices []int) ([]cliJob, error) {
	if len(indices) == 0 {
		return jobs, nil
	}
	filtered := make([]cliJob, 0, len(indices))
	seen := make(map[int]struct{}, len(indices))
	for _, idx := range indices {
		if idx < 0 || idx >= len(jobs) {
			return nil, fmt.Errorf("provider index %d out of range (0-%d)", idx, len(jobs)-1)
		}
		if _, ok := seen[idx]; ok {
			continue
		}
		clone := jobs[idx]
		filtered = append(filtered, clone)
		seen[idx] = struct{}{}
	}
	for i := range filtered {
		filtered[i].index = i
	}
	if len(filtered) == 0 {
		return nil, fmt.Errorf("no CLI providers matched selection")
	}
	return filtered, nil
}

// readInput reads from stdin and args, then combines them per CLI rules.
func readInput(stdin io.Reader, args []string) (string, error) {
	var stdinData string
	if fi, err := os.Stdin.Stat(); err == nil && (fi.Mode()&os.ModeCharDevice) == 0 {
		data, readErr := io.ReadAll(stdin)
		if readErr != nil {
			return "", fmt.Errorf("hexai: failed to read stdin: %w", readErr)
		}
		stdinData = strings.TrimSpace(string(data))
	}
	argData := strings.TrimSpace(strings.Join(args, " "))
	switch {
	case stdinData != "" && argData != "":
		return fmt.Sprintf("%s:\n\n%s", argData, stdinData), nil
	case stdinData != "":
		return stdinData, nil
	case argData != "":
		return argData, nil
	default:
		return "", fmt.Errorf("hexai: no input provided; pass text as an argument or via stdin")
	}
}

// newClientFromConfig builds an LLM client from the app config and env keys.
// client construction moved to internal/llmutils

// buildMessages creates system and user messages based on input content.
func buildMessages(input string) []llm.Message {
	lower := strings.ToLower(input)
	system := "You are Hexai CLI. Default to very short, concise answers. If the user asks for commands, output only the commands (one per line) with no commentary or explanation. Only when the word 'explain' appears in the prompt, produce a verbose explanation."
	if strings.Contains(lower, "explain") {
		system = "You are Hexai CLI. The user requested an explanation. Provide a clear, verbose explanation with reasoning and details. If commands are needed, include them with brief context."
	}
	return []llm.Message{
		{Role: "system", Content: system},
		{Role: "user", Content: input},
	}
}

// buildMessagesFromConfig uses configured CLI system prompts.
func buildMessagesFromConfig(cfg appconfig.App, input string) []llm.Message {
	lower := strings.ToLower(input)
	system := cfg.PromptCLIDefaultSystem
	if strings.Contains(lower, "explain") {
		if strings.TrimSpace(cfg.PromptCLIExplainSystem) != "" {
			system = cfg.PromptCLIExplainSystem
		}
	}
	return []llm.Message{
		{Role: "system", Content: system},
		{Role: "user", Content: input},
	}
}

// runChat executes the chat request, handling streaming and summary output.
func runChat(ctx context.Context, client llm.Client, req requestArgs, msgs []llm.Message, input string, out io.Writer, errw io.Writer) error {
	start := time.Now()
	model := effectiveModel(req, client)
	_ = tmux.SetStatus(tmux.FormatLLMStartStatus(client.Name(), model))

	output, err := runChatRequest(ctx, client, req, msgs, out)
	if err != nil {
		return err
	}

	dur := time.Since(start)
	summary := summarizeChatRun(ctx, client, model, msgs, output)
	if _, err := fmt.Fprintf(errw, "\n"+logging.AnsiBase+"done provider=%s model=%s time=%s in_bytes=%d out_bytes=%d | global Σ reqs=%d rpm=%.2f"+logging.AnsiReset+"\n",
		client.Name(), model, dur.Round(time.Millisecond), summary.sent, summary.recv, summary.snapshot.Global.Reqs, summary.snapshot.RPM); err != nil {
		return err
	}
	_ = tmux.SetStatus(tmux.FormatGlobalStatusColored(summary.snapshot.Global.Reqs, summary.snapshot.RPM, summary.snapshot.Global.Sent, summary.snapshot.Global.Recv, client.Name(), model, summary.scopeRPM, summary.scopeReq, summary.snapshot.Window))
	return nil
}

func effectiveModel(req requestArgs, client llm.Client) string {
	model := strings.TrimSpace(req.model)
	if model == "" {
		model = client.DefaultModel()
	}
	return model
}

func runChatRequest(ctx context.Context, client llm.Client, req requestArgs, msgs []llm.Message, out io.Writer) (string, error) {
	if streamer, ok := client.(llm.Streamer); ok {
		return runStreamingChat(ctx, streamer, msgs, req.options, out)
	}
	return runSimpleChat(ctx, client, msgs, req.options, out)
}

func runStreamingChat(ctx context.Context, client llm.Streamer, msgs []llm.Message, options []llm.RequestOption, out io.Writer) (string, error) {
	var output strings.Builder
	var writeErr error
	if err := client.ChatStream(ctx, msgs, func(chunk string) {
		if writeErr != nil {
			return
		}
		output.WriteString(chunk)
		if _, err := fmt.Fprint(out, chunk); err != nil {
			writeErr = err
		}
	}, options...); err != nil {
		return "", err
	}
	if writeErr != nil {
		return "", writeErr
	}
	return output.String(), nil
}

func runSimpleChat(ctx context.Context, client llm.Client, msgs []llm.Message, options []llm.RequestOption, out io.Writer) (string, error) {
	output, err := client.Chat(ctx, msgs, options...)
	if err != nil {
		return "", err
	}
	if _, err := fmt.Fprint(out, output); err != nil {
		return "", err
	}
	return output, nil
}

func summarizeChatRun(ctx context.Context, client llm.Client, model string, msgs []llm.Message, output string) chatRunSummary {
	summary := chatRunSummary{snapshot: stats.Snapshot{Window: time.Hour}}
	for _, m := range msgs {
		summary.sent += len(m.Content)
	}
	summary.recv = len(output)
	_ = stats.Update(ctx, client.Name(), model, summary.sent, summary.recv)
	snap, err := stats.TakeSnapshot()
	if err == nil {
		summary.snapshot = snap
	}
	minsWin := summary.snapshot.Window.Minutes()
	if minsWin <= 0 {
		minsWin = 0.001
	}
	if pe, ok := summary.snapshot.Providers[client.Name()]; ok {
		if mc, ok2 := pe.Models[model]; ok2 {
			summary.scopeReq = mc.Reqs
		}
	}
	summary.scopeRPM = float64(summary.scopeReq) / minsWin
	return summary
}

// printProviderInfo writes the provider/model line to stderr.
func printProviderInfo(errw io.Writer, client llm.Client, model string) {
	if strings.TrimSpace(model) == "" {
		model = client.DefaultModel()
	}
	_, _ = fmt.Fprintf(errw, logging.AnsiBase+"provider=%s model=%s"+logging.AnsiReset+"\n", client.Name(), model)
}

// newClientFromConfig is kept for tests; delegates to llmutils.
var newClientFromApp = llmutils.NewClientFromApp

// Backcompat for tests referencing the older helper name.
func newClientFromConfig(cfg appconfig.App) (llm.Client, error) { return newClientFromApp(cfg) }