package cmd

import (
	"encoding/json"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strings"

	"github.com/spf13/cobra"
	"github.com/warrenronsiek/ctask/internal/config"
	"github.com/warrenronsiek/ctask/internal/shell"
	"github.com/warrenronsiek/ctask/internal/workspace"
)

var doctorCmd = &cobra.Command{
	Use:          "doctor",
	Short:        "Verify ctask setup and diagnose configuration problems",
	Args:         cobra.NoArgs,
	SilenceUsage: true,
	RunE:         runDoctor,
}

func init() {
	rootCmd.AddCommand(doctorCmd)
}

func runDoctor(cmd *cobra.Command, args []string) error {
	passed := 0
	failed := 0

	// Check 1: Workspace root exists and is writable
	root := config.ResolveRoot()
	if info, err := os.Stat(root); err == nil && info.IsDir() {
		// Test writability by creating a temp file
		testFile := filepath.Join(root, ".ctask-doctor-test")
		if err := os.WriteFile(testFile, []byte("test"), 0644); err == nil {
			os.Remove(testFile)
			fmt.Printf("  [PASS] Workspace root exists: %s\n", root)
			passed++
		} else {
			fmt.Printf("  [FAIL] Workspace root not writable: %s\n", root)
			fmt.Printf("         Fix: check permissions on %s\n", root)
			failed++
		}
	} else {
		fmt.Printf("  [FAIL] Workspace root not found: %s\n", root)
		fmt.Printf("         Fix: create it with: mkdir %s\n", root)
		failed++
	}

	// Check 2: Default agent on PATH
	agent := config.ResolveAgent()
	if _, err := exec.LookPath(agent); err == nil {
		fmt.Printf("  [PASS] Default agent found: %s\n", agent)
		passed++
	} else {
		fmt.Printf("  [FAIL] Agent command not found: %s\n", agent)
		fmt.Printf("         Fix: install it or set CTASK_AGENT to a different command\n")
		failed++
	}

	// Check 3: Status line helper exists
	// Canonical location: %LOCALAPPDATA%\ctask\bin on Windows, ~/.local/bin on Unix.
	// Also checks GOPATH/bin as a fallback for older installs.
	statusLineFound := false
	statusLinePath := ""

	var searchPaths []string
	home, _ := os.UserHomeDir()
	gopath := os.Getenv("GOPATH")
	if gopath == "" {
		gopath = filepath.Join(home, "go")
	}
	gopathBin := filepath.Join(gopath, "bin")

	if runtime.GOOS == "windows" {
		localAppData := os.Getenv("LOCALAPPDATA")
		if localAppData != "" {
			ctaskBin := filepath.Join(localAppData, "ctask", "bin")
			searchPaths = append(searchPaths, filepath.Join(ctaskBin, "ctask-statusline.sh"))
			searchPaths = append(searchPaths, filepath.Join(ctaskBin, "ctask-statusline.ps1"))
		}
		searchPaths = append(searchPaths, filepath.Join(gopathBin, "ctask-statusline.sh"))
		searchPaths = append(searchPaths, filepath.Join(gopathBin, "ctask-statusline.ps1"))
	} else {
		searchPaths = []string{
			filepath.Join(home, ".local", "bin", "ctask-statusline.sh"),
			filepath.Join(gopathBin, "ctask-statusline.sh"),
			"/usr/local/bin/ctask-statusline.sh",
		}
	}

	for _, p := range searchPaths {
		if _, err := os.Stat(p); err == nil {
			statusLineFound = true
			statusLinePath = p
			break
		}
	}

	if statusLineFound {
		fmt.Printf("  [PASS] Status line helper found: %s\n", statusLinePath)
		passed++
	} else {
		fmt.Printf("  [FAIL] Status line helper not found\n")
		fmt.Printf("         Fix: copy ctask-statusline.sh to %s\n", searchPaths[0])
		failed++
	}

	// Check 4: Claude Code status line configured
	claudeSettingsPath := filepath.Join(home, ".claude", "settings.json")
	statusLineConfigured := false

	if data, err := os.ReadFile(claudeSettingsPath); err == nil {
		var settings map[string]interface{}
		if err := json.Unmarshal(data, &settings); err == nil {
			if sl, ok := settings["statusLine"].(map[string]interface{}); ok {
				slType, _ := sl["type"].(string)
				slCmd, _ := sl["command"].(string)
				if slType == "command" && slCmd != "" {
					// Check if the referenced file in the command exists
					// Extract the file path from the command (last argument typically)
					statusLineConfigured = true
					fmt.Printf("  [PASS] Claude Code status line configured\n")
					passed++
				}
			}
		}
	}

	if !statusLineConfigured {
		fmt.Printf("  [FAIL] Claude Code status line not configured or misconfigured\n")
		fmt.Printf("         Fix: add to %s:\n", claudeSettingsPath)
		if statusLineFound {
			// Derive the .sh path from whatever was found (could be .ps1 fallback).
			// Claude Code always needs the bash variant.
			shPath := strings.TrimSuffix(statusLinePath, filepath.Ext(statusLinePath)) + ".sh"
			bashPath := filepath.ToSlash(shPath)
			// Convert Windows drive letter for Git Bash: C:\... -> /c/...
			if len(bashPath) >= 2 && bashPath[1] == ':' {
				bashPath = "/" + strings.ToLower(string(bashPath[0])) + bashPath[2:]
			}
			fmt.Printf("         \"statusLine\": {\"type\": \"command\", \"command\": \"bash %s\"}\n", bashPath)
		} else if runtime.GOOS == "windows" {
			fmt.Printf("         \"statusLine\": {\"type\": \"command\", \"command\": \"bash /c/Users/<you>/AppData/Local/ctask/bin/ctask-statusline.sh\"}\n")
		} else {
			fmt.Printf("         \"statusLine\": {\"type\": \"command\", \"command\": \"bash ~/.local/bin/ctask-statusline.sh\"}\n")
		}
		failed++
	}

	// Check 5: Workspace root has workspaces
	results, err := workspace.ListWorkspaces(config.SearchRoots(), workspace.ListOpts{
		IncludeArchived: true,
		Limit:           0, // no limit
	})
	if err == nil && len(results) > 0 {
		activeCount := 0
		archivedCount := 0
		for _, r := range results {
			if r.Meta.Status == "archived" {
				archivedCount++
			} else {
				activeCount++
			}
		}
		fmt.Printf("  [PASS] Workspaces found: %d tasks", len(results))
		if archivedCount > 0 {
			fmt.Printf(" (%d archived)", archivedCount)
		}
		fmt.Println()
		passed++
	} else {
		fmt.Printf("  [FAIL] No workspaces found\n")
		fmt.Printf("         Fix: create one with: %s new \"my first task\"\n", invocationName())
		failed++
	}

	// Checks 6 + 7: Seed directory configuration.
	// Three states per variable:
	//   - env not set          -> informational (built-in defaults will be used)
	//   - env set, path exists -> pass
	//   - env set, path missing -> fail
	checkSeedDir(
		"General seed directory",
		os.Getenv("CTASK_SEED_DIR"),
		config.ResolveSeedDir(),
		"CTASK_SEED_DIR",
		&passed,
		&failed,
	)
	checkSeedDir(
		"Project seed directory",
		os.Getenv("CTASK_SEED_PROJECT_DIR"),
		config.ResolveProjectSeedDir(),
		"CTASK_SEED_PROJECT_DIR",
		&passed,
		&failed,
	)

	// Check 8: CTASK_PROJECT_ROOT (v0.5).
	checkProjectRoot(&passed, &failed)

	// Check 9: tmux availability for persistent session mode (v0.5.3).
	checkTmux(&passed, &failed)

	// Check 10: v0.6 — global config file + per-setting source attribution.
	// Loaded once and reused across the whole settings block so doctor
	// stays internally consistent (no re-reading the config file mid-render).
	resolver := config.LoadResolver()
	checkSettings(resolver, &passed, &failed)

	// Check 11: v0.6 — agent check when a workspace context is resolvable.
	// Uses the most-recently-active workspace (mirrors `ctask last`); skips
	// with an INFO line when no active workspace exists anywhere.
	checkAgentForDoctor(&passed, &failed)

	// Summary
	fmt.Println()
	fmt.Printf("%d checks passed, %d failed\n", passed, failed)

	if failed > 0 {
		return fmt.Errorf("%d checks failed", failed)
	}
	return nil
}

// checkProjectRoot prints the three-state CTASK_PROJECT_ROOT doctor line:
//   - unset           -> INFO pointing at the default location under CTASK_ROOT
//   - set and exists  -> INFO with custom-root advisory
//   - set and missing -> FAIL (increments failed counter)
func checkProjectRoot(passed, failed *int) {
	_ = passed // reserved for future symmetry with checkSeedDir
	envValue := os.Getenv("CTASK_PROJECT_ROOT")
	if envValue == "" {
		defaultProj := filepath.Join(config.ResolveRoot(), "projects")
		fmt.Printf("  [INFO] CTASK_PROJECT_ROOT: not set (projects discovered under %s)\n", defaultProj)
		return
	}
	resolved := config.ResolveProjectRoot()
	if info, err := os.Stat(resolved); err == nil && info.IsDir() {
		fmt.Printf("  [INFO] CTASK_PROJECT_ROOT: %s (custom -- recommended: set at user scope so all terminals can discover these workspaces)\n", resolved)
		return
	}
	fmt.Printf("  [FAIL] CTASK_PROJECT_ROOT configured but not found: %s\n", resolved)
	fmt.Printf("         Fix: create the directory or unset CTASK_PROJECT_ROOT.\n")
	*failed++
}

// checkSeedDir prints one of the three seed-directory doctor states.
// envValue is the raw value of the CTASK_SEED_* variable (empty means unset).
// resolved is the absolute path returned by the config resolver (used only
// when envValue is non-empty; for the "not configured" state the built-in
// default path is not displayed).
func checkSeedDir(label, envValue, resolved, envName string, passed, failed *int) {
	if envValue == "" {
		fmt.Printf("  [INFO] %s: not configured (using built-in defaults)\n", label)
		return
	}
	if info, err := os.Stat(resolved); err == nil && info.IsDir() {
		fmt.Printf("  [PASS] %s: %s\n", label, resolved)
		*passed++
		return
	}
	fmt.Printf("  [FAIL] %s configured but not found: %s\n", label, resolved)
	fmt.Printf("         Fix: create the directory or unset %s to use built-in defaults.\n", envName)
	*failed++
}

// checkSettings prints the v0.6 ── Settings ── block. The block shows
// the effective value of every user-level default tracked by the
// resolver, along with the source it was drawn from (built-in default,
// config file, env var, or platform override). When an env var
// overrides a config value, the override line displays both values so
// the user can see what they would inherit if they unset the env.
//
// The block also reports the config-file lifecycle state:
//   - not found        → INFO line only (no counters bumped)
//   - found, valid     → INFO line listing the path
//   - found, invalid   → FAIL line naming the offending key (failed++)
//
// Increments failed only for the invalid-config case. Passed is
// reserved for future per-setting checks (e.g., "ctask_root exists
// and is writable" — currently covered by Check 1).
//
// All values must come from the resolver, never re-read from env or
// disk inside this function — the resolver is the single source of
// truth and was already loaded once by runDoctor.
func checkSettings(r *config.Resolver, passed, failed *int) {
	_ = passed // reserved (see doc comment)
	fmt.Println()
	fmt.Println("── Settings ──────────────────────────────────")

	// Config-file lifecycle line.
	switch {
	case r.ConfigErr != nil:
		fmt.Printf("Config file: %s\n", r.ConfigPath)
		fmt.Printf("  [FAIL] %s\n", r.ConfigErr)
		fmt.Println("  Config file settings not applied — using env vars and built-in defaults only.")
		*failed++
	case r.ConfigPath != "":
		if _, err := os.Stat(r.ConfigPath); err == nil {
			fmt.Printf("Config file: %s\n", r.ConfigPath)
		} else {
			fmt.Printf("Config file: not found — using built-in defaults (%s)\n", r.ConfigPath)
		}
	default:
		fmt.Println("Config file: not found — using built-in defaults")
	}

	// Per-setting lines. Each line: `<key>: <value>` then a `source:`
	// child line. When Override is non-nil the source line names the
	// overridden source and value, matching the spec example
	// `CTASK_AGENT env var (overrides config file: claude)`.
	for _, s := range []config.ResolvedSetting{
		r.CtaskRoot(),
		r.ProjectRoot(),
		r.SeedDir(),
		r.DefaultAgent(),
		r.DefaultCategory(),
		r.SessionMode(),
		r.Editor(),
	} {
		fmt.Println()
		printSettingLine(s)
	}
}

// printSettingLine renders one ResolvedSetting as a key/value/source
// trio, including override-chain context. Extracted so future settings
// (e.g., per-workspace launch session mode in info) can reuse it.
func printSettingLine(s config.ResolvedSetting) {
	fmt.Printf("%s: %s\n", s.Key, s.Value)
	fmt.Printf("  source: %s\n", formatSettingSource(s))
	if s.Source == config.PlatformOverride && s.Override != nil {
		// Spec section 1.8 calls for an extra "configured: <value>"
		// row so the user sees what they asked for in addition to
		// what's in effect.
		fmt.Printf("  configured: %s\n", s.Override.Value)
	}
}

// formatSettingSource builds the "source: ..." annotation. The base
// label comes from the SettingSource.String(); env-var sources also
// surface the actual env-var name; PlatformOverride spells out why
// it fired; and when an override chain is present, the next-lower
// source's value is appended in parentheses so doctor renders lines
// like "CTASK_AGENT env var (overrides config file: claude)".
func formatSettingSource(s config.ResolvedSetting) string {
	var base string
	switch s.Source {
	case config.EnvVar:
		if s.EnvName != "" {
			base = s.EnvName + " env var"
		} else {
			base = "env var"
		}
	case config.PlatformOverride:
		base = "platform override (persistent mode requires tmux; not available on native Windows)"
	default:
		base = s.Source.String()
	}
	if s.Override != nil && s.Source != config.PlatformOverride {
		base += fmt.Sprintf(" (overrides %s: %s)", s.Override.Source, s.Override.Value)
	}
	return base
}

// checkAgentForDoctor runs the same validation as `ctask agents check`
// against the most-recently-active workspace. When no active workspace
// exists, prints a skip line. FAIL outcomes increment the failed counter
// (so doctor's overall exit code reflects agent breakage); WARN does not.
func checkAgentForDoctor(passed, failed *int) {
	_ = passed // reserved for future symmetry with the other checks
	fmt.Println()
	roots := config.SearchRoots()
	best, err := workspace.MostRecentActive(roots)
	if err != nil || best == nil {
		fmt.Println("Agent check:  skipped (no workspace context)")
		return
	}
	if checkErr := runAgentsCheckOnWorkspace(os.Stdout, best); checkErr != nil {
		// runAgentsCheckOnWorkspace already printed the [FAIL] lines; just
		// increment the counter so the summary reflects the breakage.
		*failed++
	}
}

// checkTmux reports the three-state tmux check (v0.5.3):
//   - CTASK_SESSION_MODE != "persistent" -> INFO (direct mode, tmux optional)
//   - persistent + tmux on PATH + version OK -> two INFO lines
//   - persistent + tmux missing or too old -> FAIL with install/update hint
func checkTmux(passed, failed *int) {
	_ = passed
	mode := config.ResolveSessionMode()
	if mode != "persistent" {
		fmt.Printf("  [INFO] Session mode: direct (tmux not required)\n")
		return
	}
	fmt.Printf("  [INFO] Session mode: persistent\n")
	tmuxPath, ver, err := shell.LookupTmux()
	if err != nil {
		fmt.Printf("  [FAIL] tmux not found on PATH or unsupported version: %v\n", err)
		fmt.Printf("         Fix: install tmux 3.0+ (apt/brew/pacman/dnf), or unset CTASK_SESSION_MODE\n")
		*failed++
		return
	}
	rawVer := ver.Raw
	if rawVer == "" {
		rawVer = "unknown version"
	}
	fmt.Printf("  [INFO] tmux found: %s (%s)\n", rawVer, tmuxPath)
}