//go:build freebsd

package target

import (
	"fmt"
	"os"
	"os/exec"
	"regexp"
	"sort"
	"strconv"
	"strings"

	procpkg "github.com/pranshuparmar/witr/internal/proc"
)

// isValidServiceLabel validates that a service name contains only
// safe characters to prevent command injection. Valid names contain only
// alphanumeric characters, dots, hyphens, and underscores.
var validServiceLabelRegex = regexp.MustCompile(`^[a-zA-Z0-9][a-zA-Z0-9._-]*$`)

func isValidServiceLabel(label string) bool {
	if len(label) == 0 || len(label) > 256 {
		return false
	}
	return validServiceLabelRegex.MatchString(label)
}

func ResolveName(name string, exact bool) ([]int, error) {
	var procPIDs []int

	lowerName := strings.ToLower(name)
	selfPid := os.Getpid()

	// Resolve own ancestry to exclude parents (sudo, shell, etc.) from matching
	ignoredPids := make(map[int]bool)
	ignoredPids[selfPid] = true
	if ancestry, err := procpkg.ResolveAncestry(selfPid); err == nil {
		for _, p := range ancestry {
			ignoredPids[p.PID] = true
		}
	}

	// Use ps to list all processes on FreeBSD
	// FreeBSD syntax: ps -axww -o pid -o comm -o args
	out, err := exec.Command("ps", "-axww", "-o", "pid", "-o", "comm", "-o", "args").Output()
	if err != nil {
		return nil, fmt.Errorf("failed to list processes: %w", err)
	}

	lines := strings.Split(string(out), "\n")
	// Skip header line (first line)
	for i, line := range lines {
		if i == 0 {
			continue // Skip header
		}

		line = strings.TrimSpace(line)
		if line == "" {
			continue
		}

		fields := strings.Fields(line)
		if len(fields) < 2 {
			continue
		}

		pid, err := strconv.Atoi(fields[0])
		if err != nil {
			continue
		}

		// Prevent matching the PID itself as a name
		if lowerName == strconv.Itoa(pid) {
			continue
		}

		// Exclude self and ancestry (parent, witr, sudo, etc.)
		if ignoredPids[pid] {
			continue
		}

		comm := strings.ToLower(fields[1])
		args := ""
		if len(fields) > 2 {
			args = strings.ToLower(strings.Join(fields[2:], " "))
		}

		// Match against command name
		var match bool
		if exact {
			match = comm == lowerName
		} else {
			match = strings.Contains(comm, lowerName)
		}
		if match {
			// Exclude grep-like processes
			if !strings.Contains(comm, "grep") {
				procPIDs = append(procPIDs, pid)
				continue
			}
		}

		// Match against full command line
		if exact {
			match = matchesExactToken(args, lowerName)
			if match && !strings.Contains(args, "grep") {
				procPIDs = append(procPIDs, pid)
			}
		} else {
			if strings.Contains(args, lowerName) &&
				!strings.Contains(args, "grep") {
				procPIDs = append(procPIDs, pid)
			}
		}
	}

	// Service detection (rc.d)
	servicePID, _ := resolveRcServicePID(name)

	// Merge and dedupe matches, keeping service PID first.
	seen := map[int]bool{}
	var procUnique []int
	for _, pid := range procPIDs {
		if pid == servicePID || seen[pid] {
			continue
		}
		seen[pid] = true
		procUnique = append(procUnique, pid)
	}
	sort.Ints(procUnique)

	var pids []int
	if servicePID > 0 {
		pids = append(pids, servicePID)
	}
	pids = append(pids, procUnique...)

	if len(pids) == 0 {
		return nil, fmt.Errorf("no running process or service named %q", name)
	}
	return pids, nil
}

// resolveRcServicePID tries to resolve a FreeBSD rc.d service and returns its PID if running.
func resolveRcServicePID(name string) (int, error) {
	// Validate input before using in command
	if !isValidServiceLabel(name) {
		return 0, fmt.Errorf("invalid service name %q", name)
	}

	// Check /var/run/<name>.pid
	pidFile := "/var/run/" + name + ".pid"
	content, err := os.ReadFile(pidFile)
	if err == nil {
		pid, err := strconv.Atoi(strings.TrimSpace(string(content)))
		if err == nil && pid > 0 {
			// Verify process exists using ps command
			out, err := exec.Command("ps", "-p", strconv.Itoa(pid), "-o", "pid=").Output()
			if err == nil && strings.TrimSpace(string(out)) != "" {
				return pid, nil
			}
		}
	}

	// Try service <name> status
	out, err := exec.Command("service", name, "status").Output()
	if err == nil {
		outStr := string(out)
		// Look for "is running as pid <number>" or "PID: <number>"
		if strings.Contains(outStr, "is running") {
			// Extract PID from output
			if idx := strings.Index(outStr, "pid "); idx != -1 {
				start := idx + 4
				end := start
				for end < len(outStr) && outStr[end] >= '0' && outStr[end] <= '9' {
					end++
				}
				if end > start {
					pid, err := strconv.Atoi(outStr[start:end])
					if err == nil && pid > 0 {
						return pid, nil
					}
				}
			}
		}
	}

	return 0, fmt.Errorf("service %q not found", name)
}
