From 59d5c96c248cb8fdeadb52e2daee8dd222547ace Mon Sep 17 00:00:00 2001
From: Chris Lane <chris@chris-allen-lane.com>
Date: Thu, 25 Jun 2020 18:21:51 -0400
Subject: [PATCH 1/3] feat(pagination): implement paginated output

Implement a `pager` config option. If configured, `cheat` will
automatically pipe output through the configured pager (where
appropriate).
---
 cmd/cheat/cmd_directories.go |  7 +++++--
 cmd/cheat/cmd_list.go        | 10 ++++++++--
 cmd/cheat/cmd_search.go      |  9 ++++++---
 cmd/cheat/cmd_tags.go        |  9 +++++++--
 cmd/cheat/cmd_view.go        |  3 ++-
 cmd/cheat/str_config.go      |  3 +++
 configs/conf.yml             |  3 +++
 internal/config/config.go    |  7 +++++++
 internal/display/display.go  | 37 ++++++++++++++++++++++++++++++++++++
 9 files changed, 78 insertions(+), 10 deletions(-)
 create mode 100644 internal/display/display.go

diff --git a/cmd/cheat/cmd_directories.go b/cmd/cheat/cmd_directories.go
index 34246d8..7b20e4c 100644
--- a/cmd/cheat/cmd_directories.go
+++ b/cmd/cheat/cmd_directories.go
@@ -1,18 +1,20 @@
 package main
 
 import (
+	"bytes"
 	"fmt"
-	"os"
 	"text/tabwriter"
 
 	"github.com/cheat/cheat/internal/config"
+	"github.com/cheat/cheat/internal/display"
 )
 
 // cmdDirectories lists the configured cheatpaths.
 func cmdDirectories(opts map[string]interface{}, conf config.Config) {
 
 	// initialize a tabwriter to produce cleanly columnized output
-	w := tabwriter.NewWriter(os.Stdout, 0, 0, 1, ' ', 0)
+	var out bytes.Buffer
+	w := tabwriter.NewWriter(&out, 0, 0, 1, ' ', 0)
 
 	// generate sorted, columnized output
 	for _, path := range conf.Cheatpaths {
@@ -25,4 +27,5 @@ func cmdDirectories(opts map[string]interface{}, conf config.Config) {
 
 	// write columnized output to stdout
 	w.Flush()
+	display.Display(out.String(), conf)
 }
diff --git a/cmd/cheat/cmd_list.go b/cmd/cheat/cmd_list.go
index 6f03318..2e41a25 100644
--- a/cmd/cheat/cmd_list.go
+++ b/cmd/cheat/cmd_list.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bytes"
 	"fmt"
 	"os"
 	"regexp"
@@ -9,6 +10,7 @@ import (
 	"text/tabwriter"
 
 	"github.com/cheat/cheat/internal/config"
+	"github.com/cheat/cheat/internal/display"
 	"github.com/cheat/cheat/internal/sheet"
 	"github.com/cheat/cheat/internal/sheets"
 )
@@ -85,10 +87,13 @@ func cmdList(opts map[string]interface{}, conf config.Config) {
 	}
 
 	// initialize a tabwriter to produce cleanly columnized output
-	w := tabwriter.NewWriter(os.Stdout, 0, 0, 1, ' ', 0)
+	var out bytes.Buffer
+	w := tabwriter.NewWriter(&out, 0, 0, 1, ' ', 0)
+
+	// write a header row
+	fmt.Fprintln(w, "title:\tfile:\ttags:")
 
 	// generate sorted, columnized output
-	fmt.Fprintln(w, "title:\tfile:\ttags:")
 	for _, sheet := range flattened {
 		fmt.Fprintln(w, fmt.Sprintf(
 			"%s\t%s\t%s",
@@ -100,4 +105,5 @@ func cmdList(opts map[string]interface{}, conf config.Config) {
 
 	// write columnized output to stdout
 	w.Flush()
+	display.Display(out.String(), conf)
 }
diff --git a/cmd/cheat/cmd_search.go b/cmd/cheat/cmd_search.go
index edc9b29..f497831 100644
--- a/cmd/cheat/cmd_search.go
+++ b/cmd/cheat/cmd_search.go
@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"github.com/cheat/cheat/internal/config"
+	"github.com/cheat/cheat/internal/display"
 	"github.com/cheat/cheat/internal/sheet"
 	"github.com/cheat/cheat/internal/sheets"
 )
@@ -87,12 +88,14 @@ func cmdSearch(opts map[string]interface{}, conf config.Config) {
 		}
 
 		// output the cheatsheet title
-		fmt.Printf("%s:\n", sheet.Title)
+		out := fmt.Sprintf("%s:\n", sheet.Title)
 
 		// indent each line of content with two spaces
 		for _, line := range strings.Split(sheet.Text, "\n") {
-			fmt.Printf("  %s\n", line)
+			out += fmt.Sprintf("  %s\n", line)
 		}
-		fmt.Println("")
+
+		// display the output
+		display.Display(out, conf)
 	}
 }
diff --git a/cmd/cheat/cmd_tags.go b/cmd/cheat/cmd_tags.go
index a17c87c..3358bdd 100644
--- a/cmd/cheat/cmd_tags.go
+++ b/cmd/cheat/cmd_tags.go
@@ -5,6 +5,7 @@ import (
 	"os"
 
 	"github.com/cheat/cheat/internal/config"
+	"github.com/cheat/cheat/internal/display"
 	"github.com/cheat/cheat/internal/sheets"
 )
 
@@ -18,8 +19,12 @@ func cmdTags(opts map[string]interface{}, conf config.Config) {
 		os.Exit(1)
 	}
 
-	// write sheet tags to stdout
+	// assemble the output
+	out := ""
 	for _, tag := range sheets.Tags(cheatsheets) {
-		fmt.Println(tag)
+		out += fmt.Sprintln(tag)
 	}
+
+	// display the output
+	display.Display(out, conf)
 }
diff --git a/cmd/cheat/cmd_view.go b/cmd/cheat/cmd_view.go
index 0636dc7..3e0aade 100644
--- a/cmd/cheat/cmd_view.go
+++ b/cmd/cheat/cmd_view.go
@@ -6,6 +6,7 @@ import (
 	"strings"
 
 	"github.com/cheat/cheat/internal/config"
+	"github.com/cheat/cheat/internal/display"
 	"github.com/cheat/cheat/internal/sheets"
 )
 
@@ -47,5 +48,5 @@ func cmdView(opts map[string]interface{}, conf config.Config) {
 	}
 
 	// display the cheatsheet
-	fmt.Print(sheet.Text)
+	display.Display(sheet.Text, conf)
 }
diff --git a/cmd/cheat/str_config.go b/cmd/cheat/str_config.go
index 6cfcd2a..f903eb6 100644
--- a/cmd/cheat/str_config.go
+++ b/cmd/cheat/str_config.go
@@ -23,6 +23,9 @@ style: monokai
 # One of: "terminal", "terminal256", "terminal16m"
 formatter: terminal16m
 
+# Through which pager should output be piped? (Unset this key for no pager.)
+pager: less -FRX
+
 # The paths at which cheatsheets are available. Tags associated with a cheatpath
 # are automatically attached to all cheatsheets residing on that path.
 #
diff --git a/configs/conf.yml b/configs/conf.yml
index a622d3e..8b9bfca 100644
--- a/configs/conf.yml
+++ b/configs/conf.yml
@@ -14,6 +14,9 @@ style: monokai
 # One of: "terminal", "terminal256", "terminal16m"
 formatter: terminal16m
 
+# Through which pager should output be piped? (Unset this key for no pager.)
+pager: less -FRX
+
 # The paths at which cheatsheets are available. Tags associated with a cheatpath
 # are automatically attached to all cheatsheets residing on that path.
 #
diff --git a/internal/config/config.go b/internal/config/config.go
index 040f645..7ae0901 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -5,6 +5,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"strings"
 
 	cp "github.com/cheat/cheat/internal/cheatpath"
 
@@ -19,6 +20,7 @@ type Config struct {
 	Cheatpaths []cp.Cheatpath `yaml:"cheatpaths"`
 	Style      string         `yaml:"style"`
 	Formatter  string         `yaml:"formatter"`
+	Pager      string         `yaml:"pager"`
 }
 
 // New returns a new Config struct
@@ -111,5 +113,10 @@ func New(opts map[string]interface{}, confPath string, resolve bool) (Config, er
 		conf.Formatter = "terminal16m"
 	}
 
+	// if a pager was not provided, set a default
+	if strings.TrimSpace(conf.Pager) == "" {
+		conf.Pager = ""
+	}
+
 	return conf, nil
 }
diff --git a/internal/display/display.go b/internal/display/display.go
new file mode 100644
index 0000000..d0930cd
--- /dev/null
+++ b/internal/display/display.go
@@ -0,0 +1,37 @@
+package display
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/cheat/cheat/internal/config"
+)
+
+// Display writes output either directly to stdout, or through a pager,
+// depending upon configuration.
+func Display(out string, conf config.Config) {
+	// if no pager was configured, print the output to stdout and exit
+	if conf.Pager == "" {
+		fmt.Print(out)
+		os.Exit(0)
+	}
+
+	// otherwise, pipe output through the pager
+	parts := strings.Split(conf.Pager, " ")
+	pager := parts[0]
+	args := parts[1:]
+
+	// run the pager
+	cmd := exec.Command(pager, args...)
+	cmd.Stdin = strings.NewReader(out)
+	cmd.Stdout = os.Stdout
+
+	// handle errors
+	err := cmd.Run()
+	if err != nil {
+		fmt.Fprintln(os.Stderr, fmt.Sprintf("failed to write to pager: %v", err))
+		os.Exit(1)
+	}
+}

From 49afd7c16b4b083ba7b16313b8a6d8981af65298 Mon Sep 17 00:00:00 2001
From: Chris Lane <chris@chris-allen-lane.com>
Date: Thu, 25 Jun 2020 18:38:03 -0400
Subject: [PATCH 2/3] feat: modify return codes

Modify exit codes. `cheat` now returns an exit code value `2` on errors
pertaining to a cheatsheet not being found.

BREAKING CHANGE
---
 cmd/cheat/cmd_list.go   | 4 ++--
 cmd/cheat/cmd_remove.go | 4 ++--
 cmd/cheat/cmd_search.go | 2 +-
 cmd/cheat/cmd_view.go   | 2 +-
 doc/cheat.1             | 7 +++++++
 doc/cheat.1.md          | 9 +++++++++
 6 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/cmd/cheat/cmd_list.go b/cmd/cheat/cmd_list.go
index 2e41a25..502fa80 100644
--- a/cmd/cheat/cmd_list.go
+++ b/cmd/cheat/cmd_list.go
@@ -81,9 +81,9 @@ func cmdList(opts map[string]interface{}, conf config.Config) {
 		flattened = filtered
 	}
 
-	// exit early if no cheatsheets are available
+	// return exit code 2 if no cheatsheets are available
 	if len(flattened) == 0 {
-		os.Exit(0)
+		os.Exit(2)
 	}
 
 	// initialize a tabwriter to produce cleanly columnized output
diff --git a/cmd/cheat/cmd_remove.go b/cmd/cheat/cmd_remove.go
index caaa09a..072e525 100644
--- a/cmd/cheat/cmd_remove.go
+++ b/cmd/cheat/cmd_remove.go
@@ -37,8 +37,8 @@ func cmdRemove(opts map[string]interface{}, conf config.Config) {
 	// fail early if the requested cheatsheet does not exist
 	sheet, ok := consolidated[cheatsheet]
 	if !ok {
-		fmt.Fprintln(os.Stderr, fmt.Sprintf("no cheatsheet found for '%s'.\n", cheatsheet))
-		os.Exit(1)
+		fmt.Fprintln(os.Stderr, fmt.Sprintf("No cheatsheet found for '%s'.\n", cheatsheet))
+		os.Exit(2)
 	}
 
 	// fail early if the sheet is read-only
diff --git a/cmd/cheat/cmd_search.go b/cmd/cheat/cmd_search.go
index f497831..3606b88 100644
--- a/cmd/cheat/cmd_search.go
+++ b/cmd/cheat/cmd_search.go
@@ -46,7 +46,7 @@ func cmdSearch(opts map[string]interface{}, conf config.Config) {
 		s, ok := consolidated[cheatsheet]
 		if !ok {
 			fmt.Printf("No cheatsheet found for '%s'.\n", cheatsheet)
-			os.Exit(0)
+			os.Exit(2)
 		}
 
 		consolidated = map[string]sheet.Sheet{
diff --git a/cmd/cheat/cmd_view.go b/cmd/cheat/cmd_view.go
index 3e0aade..2f4c550 100644
--- a/cmd/cheat/cmd_view.go
+++ b/cmd/cheat/cmd_view.go
@@ -39,7 +39,7 @@ func cmdView(opts map[string]interface{}, conf config.Config) {
 	sheet, ok := consolidated[cheatsheet]
 	if !ok {
 		fmt.Printf("No cheatsheet found for '%s'.\n", cheatsheet)
-		os.Exit(0)
+		os.Exit(2)
 	}
 
 	// apply colorization if requested
diff --git a/doc/cheat.1 b/doc/cheat.1
index 5b2c932..cc19064 100644
--- a/doc/cheat.1
+++ b/doc/cheat.1
@@ -203,6 +203,13 @@ If set, autocompletion scripts will attempt to integrate with
 \f[B]fzf\f[].
 .RS
 .RE
+.SH RETURN VALUES
+.IP "0." 3
+Successful termination
+.IP "1." 3
+Application error
+.IP "2." 3
+Cheatsheet(s) not found
 .SH BUGS
 .PP
 See GitHub issues: <https://github.com/cheat/cheat/issues>
diff --git a/doc/cheat.1.md b/doc/cheat.1.md
index f587195..eb9c1ae 100644
--- a/doc/cheat.1.md
+++ b/doc/cheat.1.md
@@ -163,6 +163,15 @@ set, all other config paths will be ignored.
 
 : If set, autocompletion scripts will attempt to integrate with **fzf**.
 
+RETURN VALUES
+=============
+
+0. Successful termination
+
+1. Application error
+
+2. Cheatsheet(s) not found
+
 
 BUGS
 ====

From fa5eb44be8d50c394cacc258084f70cbafdba37a Mon Sep 17 00:00:00 2001
From: Chris Lane <chris@chris-allen-lane.com>
Date: Thu, 25 Jun 2020 18:53:27 -0400
Subject: [PATCH 3/3] chore: bump version to 4.0.0

---
 cmd/cheat/main.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cmd/cheat/main.go b/cmd/cheat/main.go
index f9c724e..966b7ac 100755
--- a/cmd/cheat/main.go
+++ b/cmd/cheat/main.go
@@ -17,7 +17,7 @@ import (
 	"github.com/cheat/cheat/internal/installer"
 )
 
-const version = "3.10.1"
+const version = "4.0.0"
 
 func main() {